It was possibly a foreign film but I am pretty sure it was about 2 American soldiers that take refuge in a castle and there are children/orphans inside that are missing legs/arms and there is a girl wearing a mask because her face was burned. The soldiers and orphans end up fighting the German troops together. Might have been made in the 70’s. Pretty sure all the actors are no-name actors so no help there.
Is it Straight into Darkness?
http://www.imdb.com/title/tt0287733/