Play Dirty (1969)

A British Petroleum executive (Sir Michael Caine) is assigned to work with the British Army in North Africa handling port duties for incoming fuels. This gives him the official rank of captain in the British army.

The colonel (Nigel Green) in charge is told he must have a British officer accompany his men on a dangerous mission four hundred miles behind German lines and is saddled with the petroleum executive, who tries to argue his way out by saying that his contract states he is to only work port duties. That argument is lost on the brigade commander (Harry Andrews), who simply points out that the executive is wearing a British uniform. The real leader of the group (Nigel Davenport), a released prisoner, doesn't need or want the British officer, who's supposed to be in charge, but he's promised an extra two thousand pounds sterling if he gets him back alive. Disguised as Italians, their trek across Rommel's Africa includes meeting and battling many kinds of enemies.