"French knights, heavily armored (had to be lifted onto their horses with a crane)"

This is very theatrical (1944), but unfortunately historically wrong - it was only the very late period jousting armour, not war armour that was this heavy. Also jousting armour was heavier in the front side. For most of history, a fit knight was expected to get in the saddle for war with minimal assistance (you CAN actually vault from the ground unassisted into the saddle with chain (you can get very fit training for years wearing an extra 40 pounds - ask the Marines!), but surprisingly GOOD plate is not much heavier). Jousting became more popular as actual war in armour became less common - windlass crossbows could get thru plate, and when gunpowder weapons became more efficient, the interest in lugging around massive weight which was useless anyway faded. :-)