The HQ Map is a historical item that can be found by Freddie during the Battle of Marne in Chapter 1.
Location[]
When climbing down the ladder from the bridge to set the dynamite, the item is hidden behind the reeds to the right.
Description[]
"Soldiers did not have sat-nav to pick their way through the countryside. The only tools they had were a compass and a HQ map. Orienteering duties were the reserve of officers and non-commissioned officers."