The 1870-1871 Franco-Prussian War Medal (Kriegsdenkmünze für 1870/1, abbreviated KDM) was awarded to Prussian forces and allies for the war against France.  The Prussian Cabinet Order from 4 December 1871 placed the KDM 19th in precedence (of 23).  In 1895 (25th Anniversary of the War), clasps were authorized for the KDM combatants.  Those authorized were allowed to purchase the clasp(s) at approximately 35 pfennigs to almost 1 Reichsmark each, depending on the salesman's price.  The issue date is important since many KDM recipients did not receive the clasps due to death, disability, etc.  This partially accounts for the large number of KDM's on the market without clasps.  It's also important to remember that not all recipients of the KDM were authorized clasps - the clasp was an additional entitlement.  Officially, the clasps were to be worn with the 1st authorized at the top and the last on bottom but this rule was regularly ignored.  A combat clasp could not be awarded with the non-combatant steel version of the KDM nor with the non-combatant ribbon.  A review of unit histories list which battles the unit participated in and sometimes list biographical information and other awards received.   Most recipient of the official clasp also qualified for the 1897 Centenary Medal.  A review of this guide (http://reviews.ebay.com/Prussian-1897-Centenary-Medal_W0QQugidZ10000000002369985) will provide further information. 

The bronze clasps have notes which are of interest to the collector.  When clasps are present on a KDM, the manufacturing styles should match and any irregularity should be reason for suspicion.  It currently seems that there was less than 20 manufacturers of the official clasps.  It should be noted that the prices can vary considerably from dealer to dealer - especially if accompanied with other medals or documentation.  Some jeweler's copy clasps have been hallmarked.  Each clasp has different manufacturing styles:  (1) flat single ribbon width, wide lettering  (2) flat single ribbon width, narrow lettering  (3) flat 1 1/2 ribbon width, wide lettering  (4) flat 1 1/2 ribbon width, narrow lettering  (5) thick single ribbon width, hollow back, "fat" wide lettering (6) flat single ribbon width, tall & wide lettering and ca. 25% taller than the official clasps.  There are 2 different attachment methods:  (A) slip-on (B) prong back - and there are different styles to the prongs.  It's important to note that the clasp background is pebbled in all cases and is not flat or smooth (a good indicator of a copy clasp).  Another tip is that if you view the edge, it is smooth, there is no ridge showing the mold separation because the original clasps were struck from dies.  Please review my supplemental guide http://reviews.ebay.com/1870-71-Franco-Prussian-War-Medal-Unofficial-Clasps_W0QQugidZ10000000003196397 which discusses unofficial clasps which may be encountered.  Lack of space in the eBay guides prevents the two from being consolidated.   Another guide which may contain some interesting information is http://reviews.ebay.com/German-Kyffhaeuserbund-Medal_W0QQugidZ10000000002138733. 

A.MONT-VALERIEN   Note that there are a few alternate spellings.  For further information, please see:  http://reviews.ebay.com/A-MONT-VALERIEN-clasp_W0QQugidZ10000000003807748

AMIENS  For further information, please see:  http://reviews.ebay.com/AMIENS-clasp_W0QQugidZ10000000003595836 

AN DER HALLUE  For further information, please see:  http://reviews.ebay.com/AN-DER-HALLUE-clasp_W0QQugidZ10000000003594445 

AN DER LISAINE  Note that there are a few alternate spellings.  For additional information, please go to:  http://reviews.ebay.com/AN-DER-LISAINE-clasp_W0QQugidZ10000000003803042

BAPAUME  For further information, please see:  http://reviews.ebay.com/BAPAUME-clasp_W0QQugidZ10000000003595526

BEAUGENCY-CRAVANT  For further information, please see:   http://reviews.ebay.com/BEAUGENCY-CRAVANT-clasp_W0QQugidZ10000000003595348  

BEAUMONT  For further information, please see:  http://reviews.ebay.com/BEAUMONT-clasp_W0QQugidZ10000000003598978

BEAUNE LA ROLANDE  For further information, please see:  http://reviews.ebay.com/BEAUNE-LA-ROLANDE-clasp_W0QQugidZ10000000003599212

BELFORT  For further information, please see:  http://reviews.ebay.com/BELFORT-clasp_W0QQugidZ10000000003604549

GRAVELOTTE-ST.PRIVAT  For additional information, please see:  http://reviews.ebay.com/GRAVELOTTE-ST-PRIVAT-clasp_W0QQugidZ10000000003718360    

LE MANS  For further information, please see:  http://reviews.ebay.com/LE-MANS-clasp_W0QQugidZ10000000003605474

LOIGNY-POUPRY  For further information, please see:  http://reviews.ebay.com/LOIGNY-POUPRY-clasp_W0QQugidZ10000000003602272

METZ  For further information, please see:  http://reviews.ebay.com/METZ-clasp_W0QQugidZ10000000003804002 

NOISSEVILLE  For additional information, please see:  http://reviews.ebay.com/NOISSEVILLE-clasp_W0QQugidZ10000000003599057

ORLEANS  Note that there are a few alternate spellings.  For additional information, please see:  http://reviews.ebay.com/ORLEANS-clasp_W0QQugidZ10000000003697929

PARIS  For further information about this clasp, please see:  http://reviews.ebay.com/PARIS-clasp_W0QQugidZ10000000003675496

SEDAN  For further information on this clasp, please see:  http://reviews.ebay.com/SEDAN-Clasp_W0QQugidZ10000000003670910

SPICHERN  For further information, please see:  http://reviews.ebay.com/SPICHERN-clasp_W0QQugidZ10000000003811864 

ST.QUENTIN  Note that there are a few alternate spellings.  For additional information, please see:  http://reviews.ebay.com/ST-QUENTIN-clasp_W0QQugidZ10000000003827529

STRASSBURG   For further information, please see:  http://reviews.ebay.com/STRASSBURG-clasp_W0QQugidZ10000000003605797

VILLIERS  For further information, please see:  http://reviews.ebay.com/VILLIERS-clasp_W0QQugidZ10000000003599461

VIONVILLE-MARS LA TOUR   Note that there are a few alternate spellings.  For additional information, please see:  http://reviews.ebay.com/VIONVILLE-MARS-LA-TOUR-clasp_W0QQugidZ10000000003797223 

WEISSENBURG  For further information, please see:   http://reviews.ebay.com/WEISSENBURG-clasp_W0QQugidZ10000000003596159

WÖRTH   For further information, please see:  http://reviews.ebay.com/WORTH-clasp_W0QQugidZ10000000003694468

NOTES:

1. mounted KDM with AMIENS, BAPAUME, GRAVELOTTE-ST.PRIVAT & 1866 Austrian-Prussian War Medal & Centenary (specialist collection, Feb. 1991)
2. mounted KDM with WEISSENBURG, WÖRTH, SEDAN, PARIS, BEAUGENCY-CRAVANT, LE MANS, and PARIS (all Type 1B) clasps & Centenary Medal (Jun. 2005, €?)  
3. mounted 1870 Iron Cross 2nd Class (with 25th Anniversary device) & KDM with BEAUGENCY-CRAVANT & 1866 Austria-Prussian War Medal & Centenary Medal (Jan. 2006, €850) 
4. mounted Prussian Merit Medal (in silver) & KDM with LOIGNY-POUPRY, BEAUGENCY-CRAVANT, and ORLEANS & 1866 Austrian-Prussian War Medal & Centenary Medal & Landwehr Decoration (Jan. 2006, €675)
5. mounted Prussian Merit Medal (in silver) & KDM with BEAUGENCY-CRAVANT (Type 5B) & 1866 Austrian-Prussian War Medal & Centenary Medal & Landwehr Decoration (Sep. 2006, €745)
6. mounted KDM with ORLEANS, BEAUGENCY-CRAVANT (both Type 1B) clasps and Centenary Medal (Oct. 2006, €28.50)
7. KDM with LOIGNY-POUPRY, BEAUGENCY-CRAVANT, and LE MANS (Oct. 2006, GBP120) 
8. KDM with COLOMBY-NOUILLY (Type 1B), Gravelotte-St.Privat (Type 1B), and SPICHEREN (Type 5B) (private collection, Feb. 2001) 
9. KDM with COLOMBEY-NOUILLY and METZ (Sep. 2002, €75)
10. KDM with COLOMBEY-NOUILLY and METZ (both Type 3B) (Sep. 2005, €100)
11. KDM with COLOMBEY-NOUILLY and METZ (Type 1B) (Oct. 2006, €75 - damaged)
12. mounted KDM with GRAVELOTTE-ST.PRIVAT and METZ & 1866 Austria-Prussian War Medal & Centenary Medal (specialist collection, Nov. 2006)
13. KDM with GRAVELOTTE ST. PRIVAT and COLOMBEY-NOILLY (both Type 1B) (Oct. 2006, €75)
14. KDM ribbon with METZ, GRAVELOTTE-ST. PRIVAT, ORLEANS, and LE MANS (all Type 2B) (Oct. 2006, specialist collection)
15. KDM with LOIGNY-POUPRY, BEAUGENCY-CRAVANT, and ORLEANS (Jan. 2006, €145)
16. KDM with PARIS, ORLEANS, and SEDAN (private collection, Nov. 2002), (Jan. 2007, €150).
17. mounted 1870 Iron Cross 2nd Class (with 25th Annivarsary device) & Prussian War Aid Cross & KDM with ORLEANS (Type 1B, 4 holes drilled in each corner and sewn on) & Centenary Medal (specialist collection, Nov. 2006)
18. mounted KDM with PARIS & Centenary Medal (Oct. 2006, $245)
19. mounted KDM with VILLIERS and PARIS & SW Africa Medal (non-combatant) & Centenary Medal (specialist collection, Nov. 2006)
20. mounted 1870 Iron Cross 2nd Class (with 25th Anniversary device) & KDM with SEDAN, WÖRTH, plus 2 clasps & Centenary Medal (Jan. 2006, €1250)
21. mounted KDM with WEISSENBURG & Centenary Medal (Jan. 2006,  €150)
22. 1870 Iron Cross 2nd Class (25th Anniversary device not present) & Prussian Merit Medal (in silver) & KDM with WÖRTH & Centenary Medal & Landwehr Decoration (Sep. 2006, €1500)
23. mounted 1870 Iron Cross 2nd class (25th Anniversary device) & Order of the Red Eagle 4th Class (with swords) & Prussian Lifesaving Medal, KDM with PARIS & 1866 Austrian-Prussia War (Königgratz) & Centenary Medal & Mecklenburg-Schwerin 1870 Military Service Cross & Württemburg 1884 King Karl 25-year Jubilee Medal & Turkey 1889 Kaiser Wilhelm II Visit to Konstantinopel (in gold) (Apr. 2004, €2,500)
24. mounted KDM with WÖRTH (Type 2B) & Centenary Medal (Nov. 2006, €100 - damaged)
25. mounted KDM with AMIENS, GRAVELOTTE-ST.PRIVAT, BAPAUME (all Type 1B) & 1866 Austrian-Prussian War Medal & Centenary Medal (28th Prussian Infantry specialist collection, 1991)
26. mounted KDM with GRAVELOTTE (Type 6B), PARIS (Type 5B), SEDAN (Type 5B), BEAUMONT (Type 5B), LE BOURGET (Type 5B) & Hohenzollernschen Kriegbundes Kreuz & Centenary Medal & Landwehr Decoration - the KDM and Centenary Medal are mounted on each other's ribbon while the HKK is mounted on a KDM centered with the 5 clasps in 3 rows spanning the entire KDM ribbons width (on display March 2007 and prior, Museum des Wasserschlosses Glatt bei Sulz am Nekar)
27. mounted Iron Cross 2nd Class with 25 oakleaf device,  KDM with PARIS, SEDAN & 1897 Centenary Medal & Landwehr Long Service Badge 2nd Class, Kyffhäuserbund Medal with +PARIS+, +SEDAN+, crossed swords (private German collection, ?-2004-2006-?)
28. remounted KDM with PARIS (Type 1B) & 1897 Centenary Medal & Kyffhäuserbund Medal (private German collection, ?-2004-2006-?)

Copies and forgeries abound.  Most copies (typically cast) are made for collectors or re-enactors who require an example.  Jeweler's copies are known and are not highly regarded even if they are verified contemporary - but many sellers do not make the distinction clear.  There are a series of clasps of almost the same style and with the same names which were awarded by veteran organizations for service in WWI.  In some cases, a clasp exist for a 1870-71 battle and no WWI battle occurred there.   

• One explanation is that some of these were for the Franco-Prussian War veterans to wear on their post-WWI veteran medal (for instance, the Kyffhauserbund Medal) since most of these organizations accepted all veterans.  A specialist can readily spot these by examining the background and the prong design but most collectors are easily fooled.  Collecting these post-WWI clasps for Franco-Prussian War actions is a very rare field which offers great potential.  However, the collector should realize that these clasps are missidentified about 99% of the time and needs to pay close attention to the clasp style. 

Medal Group with KDM & clasp

Again, the best advice is:  Buy only from a reputable dealer who specializes in Prussian medals.  Please visit my blog (http://blogs.ebay.com/tsa-li) and/or guides for further information.  Thank you for your visit!