The Bar of Soap is a historical item which can be found by Anna in the hospital of Saint Mihiel during Chapter 4.
Location[]
After arriving at the hospital, head outside through the door on the right and collect this hidden item from behind the bush.
Description[]
"Soap was the basis for all hygiene. It was obviously used to wash, but also for washing clothes and mess tins. How it was made depended on local recipes, and it soon became a rare commodity during the war as oil became scarcer."