R.O.A. is a German Infantry unit added in Back to Hell.
Considered generally a part of the Osttruppen, ROA was officially formed in autumn 1944, as the situation rapidly deteriorated from desperate to catastrophic. It did not play a major role due to being understaffed and undersupplied.
During the Liberation of Paris there was a company of ROA troops that didn't execute partisans (or suspects of being partisans) jailed in the city prisons.
ROA are stronger at close range, and their high unit health makes them sturdier than virtually all other units they will face at 100m. They are reliable units fielded by the Festung Groß-Paris and should fight where the division's second rate troops would get mauled by better infantry or armor.