Hi aacoins, and welcome to the forum. Friedrich Willhelm II was the King of Prussia in 1788 (which I think is the date on your piece), but Google doesn't turn up anything particularly significant in Prussian history about August 25, 1788. With the token/medal/jeton in hand, can you confirm its date? Also, what (if anything) is on the other side? The legend seems to pick up in the middle of a statement, not mentioning what thing worthy of commemoration was done "by the Valiant King of Prussia" on that date
Possibly in reference to the Battle of Zorndorf, where the Prussians defeated the Russians on Aug 25, 1758? http://www.nationmaster.com/encyclopedia/Battle-of-Zorndorf
