I was at Les Invalides yesterday and many of the Prussian cuirassier helmets had large "RF" emblazoned on them (some along with "Mit gott fur kaiser und vaterland"). What does RF stand for?

by theotherpena

It was in Salle Alsace-Lorraine, in the 1870-1890 sort of era

brettmjohnson

They were actually emblazoned with "FR", not "RF". FR stands for "Fredericus Rex", the latinized version of "King Frederick". (7 of Prussia's 9 kings were named Frederick).

"Mit gott fur Koenig/Kaiser un Vaterland" translates directly as "With God for King/Emperor and Fatherland", or the more familiar "With God, for King and country."