The first thing to know is specifically, what is a blacklight?  A blaclight is a light source specifically designed ro primarily emit near-ultraviolet light, along with a small amount of visible light in the indigo range.  Due to the nature of the light emitted, they produce virtually no illumination, unless yoo are very close to the source.  They come in two varities, flourescent and incandescent bulbs.  Both bulbs are characterized by the use of a deep blue-purplish glass envelope called 'Wood's Glass'.  While the incandescent bulb is a cheaper alternative to fluorescent bulbs, rhey are exceptionally inefficient at producing UV light (a mere few lumens per watt) owing to the nature of the incandescent light source.  It is for this reason that I recommend you invest in, and use flourescent blacklight bulbs for your ribbon testing, as incandescent bulbs, when producing so little UV radiation, may be unable to produce a true or visable test result.

  What does blacklighting do?  It has to do with the nature of the threads used in the production of the ribbon in question.  Natural material ribbons, such as those made of silk or cotton, are colored to the core by dyes.  Ribbons made with natural fibers are quite opaque in nature to UV light, and tend to appear flat or dark in color when exposed to an UV light source.  Artifical, or man-made fibers, such as nylon or rayon on the other hand, are literally plastic in nature, and are tranclucent to UV radiation.  What this means is, while the ultraviolet radiation itself is invisible to the human eye, illuminating certain materials with UV radiation prompts the visible effects of fluorescence and phosphorescence.  Most of us have seen the results of this at a Discothèque, when the DJ's switch from normal lighting to black lighting, and people's clothes begin to seemingly 'glow' like a neon bulb.

  Black light testing is commonly used to authenticate antiques.  To test your ribbon, turn off all sources of visible light.  Best results can be had in a darkroom, or any room during nighttime hours.  A ribbon that appears to glow or displays fluoresence is testing positive for the presence of artificial, or man-made fibers.  By knowing what the ribbon is made of, it can help you date it.  Artificial fibers generally became available after 1950, as production methods were refined to make their cost competative, or lower than natural fibers.  Nylon was invented in 1935, but its high-priority use in war munitions and parts make use as ribbon fiber a post-WWII reality.  And Rayon, while invented in 1855, the original production process was similar to producing nitroglycerine, which made the resultant fiber highly flammable!  A commercially viable and safe Rayon was eventually introduced in the mid-1930's.  As a general rule of thumb. pre-WWII - expect and accept only natural fiber ribbons on your medals.  WWII-Korean War era, artificial fiber ribbons are possible, but unusual.  Be sure to ensure the medal itself passes scrutiny!  Post-Korean War, artifical fiber ribbons became commonplace.

  Care in using blacklights:  Blacklights do emit a very small amount of UVA radation.  UVA is capable of causing damage to collagen fibers, so it does have the potential to accelerate skin aging and cause wrinkles. UVA can also destroy vitamin A in the skin.  UVA light can also cause DNA damage.  However, the strength of a black light in comparison to sunlight is minuscule, so it is doubtful that the periodic use of an UVA light poses any significant health risks. The weak output of black lights should also not cause DNA damage or cellular mutations the way sunlight can.  A greater concern in the use of blacklights is heat generation during use.  This is a particular concern when using incandescent blacklight bulbs, due to the inefficient way they produce blacklight.  For this reason, be sure to provide adequate ventilation to your blacklight source.

COMBAT CLASPS
 A Combat Clasp is denoted by having a star at either end of the bar.  I have also included the number of days the particular battle lasted. and the number of KNOWN Divisions or Regiments involved.  A Regiment is roughly up to 5,000 soldiers, while a Division is approximately 15,000 soldiers.  This will give you a rough indication of the scarcity of each Combat Clasp listed.

Cambrai: May 20 to December 4, 1917                      (198 Days of Combat - 3 Regiments)
Somme Defensive: March 21 to April 6, 1918             (  16 Days of Combat - 1 Regiment)
Lys: April 9 to 27, 1918                                            (  18 Days of Combat - Units from 4 Divisions)
Aisne: May 27 to June 5, 1918                                  (    9 Days of Combat - 2 Divisions)
Montdidier-Noyon: June 9 to 13, 1918                        (    4 Days of Combat - 1 Division)
Champagne-Marne: July 18 to August 6, 1918            (  19 Days of Combat - 4 Divisions)
Aisne-Marne: July 18 to August 6, 1918                     (  19 Days of Combat - 8 Divisions)
Somme Offensive: August 8 to November 11, 1918      (  95 Days of Combat - 3 Divisions)
Oise-Aisne: August 18 to November 11, 1918              (  85 Days of Combat - 3 Divisions)
Ypres-Lys: August 19 to November 11, 1918               (  84 Days of Combat - 4 Divisions)
St. Mihiel: September 12 to 16, 1918                          (    4 Days of Combat - 13 Divisions)
Meuse-Argonne: September 26 to November 11, 1918  (  46 Days of Combat - 25 Divisions)
Vittorio-Veneto: October 24 to November 4, 1918         (   11 Days of Combat - 1 Regiment)
Defensive Sector: For participation in any 'minor' battle that is not honored with any of the above 'named' Combat Clasps:
     April 6, 1917 to November 11, 1918                       (584 Eligible Days - Typically for 1 Day of Combat - 2 Divisions, plus anyone engaged or wounded in combat)

SERVICE CLASPS
 A Service Clasp is denoted by not having stars on the ends of the clasp.  Again, the KNOWN number of eligible units are indicated).  Service Clasps were given basically "for being there".

England: April 6, 1917 to November 11, 1918 (References state ±30,100 issued)
France: April 6, 1917 to November 11, 1918 (12 Divisions - References state ±621,000 issued)
Italy: April 6, 1917 to November 11, 1918 (Support units from the 83rd Division - References state ±4,800 issued)
Russia: Any service in European Russia (3 Battalion to Regiment sized units from the 85th Division - References state ±9,000 issued)
Siberia: Any service in Siberia or Asian Russia (Volunteers from 5 Regiments - References state ±9,000 issued)

 The US Selective Service Records indicate 2,810,296 individuals were inducted during WWI, of which ±62,000 served in the US Navy.  As nearly 2,000,000 American servicemen in the A.E.F. (American Expeditionary Force) had reached Europe (primarily France) prior to the cessation of hostilities on November 11th, 1918, and the approximate issue of Medals with a Service Clasp (from above) was ±673,000, this means ±1,326,000 WWI Victory Medals were issued with one (or more) Combat Clasps, and ±748,000 were issued with no clasps, indicating stateside service only.

 Unlike the U.S. Navy and Marine Corps, the U.S. Army did allow the wearing of multiple Combat Clasps.  If an individual qualified to wear more than one clasp, the recipient was allowed to wear the clasp.  The exception being the wearing of a Service Clasp and a Combat Clasp.  A Combat Clasp is presumed to take precidence over a Service Clasp, so therefore, if anyone was authorized a Combat Clasp, they recieve that instead of a Service Clasp.  The most common way to upgrade to a Battle Clasp was to be awarded the Defensive Sector Clasp for being wounded.  This is what occured with my Uncle, who served with the 41st Division.  Since he was exposed to a gas attack (wounded), he became eligible for a Defensive Sector Combat Clasp vs a France Service Clasp.  Bottom line - any offering of a multi-clasp medal with Service and Battle Clasps combined are made-up combinations.  Also, the U.S. Army did not allow the wearing of multiple Service Clasps - if you were eligible for two Service Clasps, you only got to choose one for award and wearing.  That leaves the question of which combination of Combat Clasps are legitimate?  Not every clasp can be worn together.  Some are date exclusive, especially for Infantry or Marine units - you were either at one battle, or the other.  For example, you will never see an Infantry unit with the Oise-Asine and Ypres-Lys Battle Clasps together (however an Artillery unit, which spanned both battle fronts, DID recieve this unusual combination).

  The following is a list of the authorized clasps for the larger Army units raised during WWI.  Remember to add the Defensive Sector Battle Clasp mentally to every unit authorized any Battle Clasps.  If a unit was only eligible for the Defensive Sector Battle Clasp, then it will be the only clasp listed.  Also remember - this is a listing of UNIT eligibility.  For specific INDIVIDUALS, they would have had to participate in every specific battle honored with a Battle Clasp to earn the right to wear that clasp.

  With this knowledge, it is obvious that the most Battle Clasps an individual could have earned on any one medal is seven (by personnel in the 3rd Division, 6th Engineers).  Realistically, anything above three Battle Clasps is an outstanding accomplishment, by WWI standards.  With this list, you should have a start in identifing which unit the recipient of the medal with multiple clasps served in, as certian combinatons will only be found within certian units.  If a Battle or Service Clasp is UNIQUE to a unit - it will be denoted with a *U* following the name of the clasp.

1st Division  Montdidier-Noyon - *U*  Aisne-Marne  St. Mihiel  Meuse-Argonne	2nd Division  Aisne  Aisne-Marne  St. Mihiel  Meuse-Argonne	3rd Division (Most of Division - exceptions follow)  Aisne  Champagne-Marne  Aisne-Marne  Meuse-Argonne	3rd Division, 3rd Ammunition Train  Ineligible for Aisne
3rd Division, 3rd Field Artillery Brigade  Add - St. Mihiel  Ineligible for Asine	3rd Division, 7th Machine Gun Batallion  Add - St. Mihiel	3rd Division, 6th Engineers Regiment  Add - St. Mihiel  Add - Somme Defensive	4th Division (Most of Division - exception follows)  Aisne-Marne  St. Mihiel  Meuse-Argonne
4th Division, 4th Field Artillery Brigade, 77th Field Artillery Battery  Ineligible for Aisne-Marne	5th Division (Most of Division - exception follows)  St. Mihiel  Meuse-Argonne	5th Division, 5th Field Artillery Brigade  Ineligible for Meuse-Argonne	6th Division  Meuse-Argonne
7th Division  Meuse-Argonne	8th Division  No Clasps Authorized	26th Division  Champagne-Marne  Aisne-Marne  St. Mihiel  Meuse-Argonne	27th Division (Most of Division - exception follows)  Ypres-Lys  Somme Offensive
27th Division, 52nd Field Artillery Brigade  Add - Meuse-Argonne  Ineligible for Ypres-Lys  Ineligible for Somme Offensive	28th Division (Most of Division - exception follows)  Champagne-Marne  Aisne-Marne  Oise-Aisne  Meuse-Argonne	28th Division, 53rd Artillery Brigade  Add - Ypres-Lys  Ineligible for Champagne-Marne  Ineligible for Aisne-Marne	29th Division  Meuse-Argonne
30th Division  Ypres-Lys  Somme Offensive	31st Division  France Service Clasp	32nd Division  Aisne-Marne  Oise-Aisne  Meuse-Argonne	33rd Division (Most of Division - exception follows)  Somme Offensive  Meuse-Argonne
33rd Division, 58th Field Artillery Brigade  Add - St. Mihiel  Ineligible for Somme Offensive	34th Division  France Service Clasp	35th Division (Most of Division - exception follows)  Meuse-Argonne	35th Division, 60th Field Artillery and the 69th and 70th Infantry Brigades, 110th Engineers, and the 110th Field Signal and 128th Machine Gun Batallions  Add - St. Mihiel
36th Division (Most of Division - exception follows)  Meuse-Argonne	36th Division, 111th Engineers  Add - St. Mihiel	37th Division (Most of Division - exception follows)  Meuse-Argonne  Ypres-Lys	37th Division, 62nd Field Artillery Brigade  Ineligible for Ypres-Lys
38th Division  France Service Clasp	39th Division  France Service Clasp	40th Division  France Service Clasp	41st Division  France Service Clasp
42nd Division  Champagne-Marne  Aisne-Marne  St. Mihiel  Meuse-Argonne	76th Division  France Service Clasp	77th Division  Oise-Aisne  Meuse-Argonne	78th Division  Meuse-Argonne  St. Mihiel
79th Division  Meuse-Argonne	80th Division (Most of Division - exceptions follow)  Meuse-Argonne	80th Division, 159th and 160th Infantry Brigades, 305th Engineers, and the 305th field Signal and 313th Machine Gun Batallions  Add - St. Mihiel	80th Division, No Specific Unit Cited - Possibly entire Division (Reference: G.O. #75, G.H.Q., A.E.F., May 2nd, 1919)  Add - Somme Offensive
81st Division  Meuse-Argonne	82nd Division  St. Mihiel  Meuse-Argonne	83rd Division  France Service Clasp	84th Division  France Service Clasp
85th Division  France Service Clasp	85th Division. 1st Battalion  Russia Service Clasp	85th Division, 339th Infantry Regiment  Russia Service Clasp	85th Division, 339th Infantry Regiment  Russia Service Clasp
85th Division, 310th Engineer Train  Russia Service Clasp	86th Division  France Service Clasp	87th Division  France Service Clasp	88th Division  Meuse-Argonne
89th Division (Most of Division - exception follows)  St. Mihiel  Meuse-Argonne	89th Division, 164th Field Artillery Brigade  Defensive Sector only  Ineligible for St. Mihiel  Ineligible for Meuse-Argonne	90th Division  St. Mihiel  Meuse-Argonne	91st Division  St. Mihiel  Meuse-Argonne  Ypres-Lys
92nd Division Meuse-Argonne	93rd Division  No Clasps Authorized* (See Footnote Below) 11th Engineer Regiment  Cambrai	12th Infantry Regiment (Few Volunteers)  Siberia Service Clasp	12th Engineer Regiment  Cambrai
13th Infantry Regiment (Many Volunteers)  Siberia Service Clasp	14th Engineer Regiment  Cambrai	27th Infantry Regiment  Siberia Service Clasp	31st Infantry Regiment  Siberia Service Clasp
62nd Infantry Regiment (Many Volunteers)  Siberia Service Clasp	332nd Infantry Regiment  Vittorio-Veneto - *U*	369th Infantry Regiment  Champagne-Marne  Aisne-Marne  Meuse-Argonne	370th Infantry Regiment  St. Mihiel  Oise-Aisne
371st Infantry Regiment  Meuse-Argonne	57th Field Artillery Brigade  Aisne-Marne  Oise-Marne  Meuse-Argonne	66th Field Artillery Brigade  Champagne-Marne  Aisne-Marne  St. Mihiel  Meuse-Argonne	158 Field Artillery Brigade and the 3rd Corps Artillery Park  Meuse-Argonne
1st Corps Artillery Park  Champagne-Marne  Aisne-Marne  Oise-Marne  Meuse-Argonne	2nd Corps Artillery Park  Aisne-Marne  Oise-Marne  St. Mihiel  Meuse-Argonne	4th Corps Artillery Park and the 58th Artillery, Coast Artillery Corps  Defensive Sector	1st Army Artillery Park plus the 43rd, 51st, 53rd, 57th, 59th, 60th, and the 65th Artillery, Coast Artillery Corps  St. Mihiel  Meuse-Argonne
42nd Artillery, Coast Artillery Corps  Champagne-Marne	44th Artillery, Coast Artillery Corps  Champagne-Marne  St. Mihiel  Meuse-Argonne	52nd Artillery, Coast Artillery Corps, the 1st Gas Regiment, and the 1st Batallion, Trench Artillery  Aisne-Marne  St. Mihiel  Meuse-Argonne	55th and 56th Artillery, Coast Artillery Corps  Oise-Marne  Meuse-Argonne
2nd Cavalry Division  Aisne-Marne  St. Mihiel  Meuse-Argonne	1st and 2nd Antiaircraft Batallion plus the 1st and 2nd Antiaircraft Machine Gun Battalion  St. Mihiel  Meuse-Argonne	115th and the 301st Field Signal Batallion  Defensive Sector	308th Field Signal Batallion  Aisne-Marne  Oise-Marne  Meuse-Argonne
310th Field Signal Batallion  St. Mihiel	317th and the 319th Field Signal Batallion  St. Mihiel  Meuse-Argonne	318th Field Signal Batallion  Somme Offensive	322nd Field Signal Batallion  Champagne-Marne  Aisne-Marne  St. Mihiel  Meuse-Argonne
11th Engineers (Standard Guage RR)  Lys	12th Engineers (Light RR)  Somme Defensive	13th Engineers (Standard Guage RR) plus the 115th Engineers  Defensive Sector	14th Engineers (Light RR)  Somme Defensive  Aisne-Marne  Oise-Marne  Meuse-Argonne
15th Engineers (Standard Guage RR) and the 21st Engineers (Light RR) plus Independant Engineers - 23rd (Highway), 24th (Supply & Shop), 26th (Water Supply), 28th (Quarry), 37th (Electrical & Mechanical), 56th (Searchlight), 310th, and the 602nd  St. Mihiel  Meuse-Argonne	16th Engineers (Standard Guage RR)  Lys  Meuse-Argonne	22nd Engineers (Light RR) plus Independant Engineers - 25th (Construction), 27th (Mining), 114th, 603rd, and the 604th  Meuse-Argonne	Independant Engineers - 29th (Survey & Print) and the 40th (Camoflage)  Aisne-Marne  St. Mihiel  Meuse-Argonne
301st Engineers  St. Mihiel	308th Engineers  Aisne-Marne  Oise-Marne  Meuse-Argonne	1st Pioneer Infantry  Aisne-Marne  Oise-Aisne  Meuse-Argonne	3rd, 52nd, 54th, 56th, 59th, 802nd, 805th, 806th, 807th, and the 808th Pioneer Infantry  Meuse-Argonne
51st Pioneer Infantry  St. Mihiel	53rd Pioneer Infantry  St. Mihiel  Meuse Argonne	803rd and the 804th Pioneer Infantry  Defensive Sector	51st, 409th, 417th, and the 419th Telegraph Batallion  Defensive Sector
52nd Telegraph Batallion  Aisne-Marne  Oise-Marne  Meuse-Argonne	55th and the 401st Telegraph Batallion  St. Mihiel  Meuse-Argonne	406th and the 411th Telegraph Batallion  Aisne-Marne  St. Mihiel  Meuse-Argonne	412th Telegraph Batallion  Ypres-Lys  Somme Offensive
301st Batallion, Tank Corps  Somme Offensive	344th and the 345th Batallion, Tank Corps  St. Mihiel  Meuse-Argonne	1st Corps Observation Group (Most of Group - exception follows)  Champagne-Marne  Aisne-Marne  St. Mihiel  Meuse-Argonne	1st Corps Observation Group, 50th Squadron  Ineligible for Champagne-Marne  Ineligible for Aisne-Marne
3rd Corps Observation Group (Most of Group - exceptions follow)  Champagne-Marne  Aisne-Marne  St. Mihiel  Meuse-Argonne	3rd Corps Observation Group, 90th Squadron  Ineligible for Champagne-Marne  Ineligible for Aisne-Marne	3rd Corps Observation Group, 199th Squadron  Ineligible for Champagne-Marne  Ineligible for Aisne-Marne  Ineligible for St. Mihiel	4th Corps Observation Group (Most of Group - exception follows)  St. Mihiel
4th Corps Observation Group, 168th Squadron  Defensive Sector Only  Ineligible for St. Mihiel	5th Corps Observation Group plus 1st Army Observarion Group (Most of Group - exception follows) and the 1st Day Bombardment Group (Most of Group - exception follows)  St. Mihiel  Meuse-Argonne	1st Army Observarion Group, 186th Squadron and the 1st Day Bombardment Group, 166th Squadron  Ineligible for St. Mihiel	6th and 7th Corps Observation Group, plus the 2nd Day Bombardment Group  Defensive Sector
1st Pursuit Group (Most of Group - exceptions follow)  Champagne-Marne  Aisne-Marne  St. Mihiel  Meuse-Argonne	1st Pursuit Group, 185th Squadron  Ineligible for Champagne-Marne  Ineligible for Aisne-Marne  Ineligible for St. Mihiel	1st Pursuit Group, 4th Air Park  Ineligible for Champagne-Marne  Ineligible for Aisne-Marne	2nd Pursuit Group (Most of Group - exceptions follow)  St. Mihiel  Meuse-Argonne
2nd Pursuit Group (Most of Group - exceptions follow)  St. Mihiel  Meuse-Argonne	2nd Pursuit Group, 22nd Squadron  Add - Somme Defensive	2nd Pursuit Group, 5th Air Park  Ineligible for St. Mihiel	3rd Pursuit Group (Most of Group - exception follows)  St. Mihiel  Meuse-Argonne
3rd Pursuit Group. 28th Squadron  Add - Somme Defensive  Add - Lys	4th Pursuit Group (Most of Group - exceptions follow)  Somme Defensive  Somme Offensive	4th Pursuit Group, 141st Squadron and the 6th Air Park  Defensive Sector only  Ineligible for Somme Defensive  Ineligible for Somme Offensive	1st Corps Balloon Group (Most of Group - exceptions follow)  Aisne-Marne  St. Mihiel  Meuse-Argonne
1st Corps Balloon Group, 2nd Balloon Company  Add - Champagne-Marne	1st Corps Balloon Group, 5th Balloon Company  Ineligible for Aisne-Marne	3rd Corps Balloon Group (Most of Group - exceptions follow) and all of the 5th Corps Balloon Group, Army Balloons - 1st Army, and 3rd Air Park  St. Mihiel  Meuse-Argonne	3rd Corps Balloon Group, 4th Balloon Company  Add - Aisne-Marne  Ineligible for St. Mihiel3rd Corps Balloon Group, 4th Balloon Company  Add - Aisne-Marne  Ineligible for St. Mihiel
4th Corps Balloon Group (Most of Group - exceptions follow)  Defensive Sector	4th Corps Balloon Group, 69th Balloon Company  Add - St. Mihiel	6th Corps Balloon Group  St. Mihiel

 I have yet to find any specific unit authorized the England or Italy Service Clasps.  For Italy, however, it is most likely to be units from the 83rd Division in support of the 332nd Infantry Regiment.

* A sad commentary on the mindset of the times.  President Wilson and General Pershing had demanded all American units be kept under American command, much to the chagrin of our Allies who wished to piecemeal plug in American units as they arrived, wherever thay were "needed".  This is a precident that has continued to this day.  However, as a "colored" (read that as expendable) unit, the 93rd Division was "allowed" to be placed under French command for the duration of the war.  Because they were not under "American" command during the war, they were deemed ineligible for ANY clasp that would have been normally issued to any other unit, be it Combat or Service.  It is an inequity that has not been corrected to this day.

 Much of this information was consolidated from various internet sources, and the period reference "Battle Participation of Organizations of the American Expeditionary Forces in France, Belgium and Italy 1917-1918" by the US War Office, 1920.

Atlantic Fleet - 43,185
Transport - 33,505
Armed Guard - 22,381
Aviation - 15,000
Escort - 20,381
Destroyer - 10,000
Sub Chaser - 8,451
Grand Fleet - 7,500
Overseas - 7,500
Patrol - 7,500
Mobile Base 3,646
Mine Laying - 3,294
Mine Sweeping - 3,294
Submarine - 3,294
Asiatic - 1,000
White Sea - 1,000
Naval Battery - 817
Salvage - 817
West Indies - Number Uncertian - Authorizatization and distribution began in 1921

 Two clasps, the Hospital Ship, and the Gunboat clasps were mentioned in the original orders for the medal, but were never authorized for award.  Several other clasps, strictly unauthorized, and privately made and affixed, have surfaced on the Navy WWI Victory Medal.
 All of the clasps were represented by a bronze star when the ribbon bar was worn - a minature of the clasp was never used.  In addition, a Silver Star could be worn on the ribbon of the medal or ribbon bar for a citation of gallantry not justifying an award of the Medal of Honor, Navy Cross, or Navy Distinguished Service Medal.  This Silver Star Device was the genesis of the future Silver Star Medal, and all personnel recieving the Silver Star Device were authorized to trade that award for the Silver Star Medal when it was authorized in 1932.  A final ribbon device, a bronze Maltese Cross, was authorized for any individual attached to the American Expeditionary Force, but were not authorized to recieve one of the Army battle clasps.  It may be possible that the Maltese Cross device might be found with one of the Army service clasps, but the Navy authorization for these clasps was slow in coming (the Russia and Siberia clasps were authorized for wear in 1933; and the England, France, and Italy clasps were authorized in 1940), and the eligible recipient would have had to apply for the newly authorized clasp.