As long as there have been vehicles in combat, there have been improvised efforts to make them more capable of dealing with the challenges they faced. Tanks in WWII would carry logs to be used to help get tanks unstuck when they got bogged down, some aircrews of US bombers would sit on their flak jackets or get armor plating installed in their seats or the floors under their stations because "they knew what they wanted to protect" (note: armor you sit or stand on is of limited use in a three-dimensional battlefield, but it does help your morale), British merchant Cruisers would carry loads of cork to make them harder to sink because they were not made to shrug off battle damage, crews of PBY Catalinas would make up for the flying boat's relative lack of armament by tossing mortar rounds and other man-portable explosives out of a hatch during harassment raids, etc.

Hell, just look at the evolution of the B-17 Flying Fortress from sleek Art Deco work of art to battle-hardened gunship, with three or four additional gun turrets and machine guns sticking out of random windows to improve their protection just a bit.