June 24, 1812, Napoleon’s army began to cross the Nieman River on the three pontoon bridges his engineers has built the night before. They were unopposed when they reached the eastern bank.
Pontoon bridges were of loose construction (not lashed together tightly) so they could move up and down in the water to take the weight of the troops, wagons and artillery. Men were not permitted to march on the bridge, but instead had cross at the route step to even out the stress. Horses, who never marched in step, were not a problem.
Image and translation of Commemorative 1912 card provided by Alexey Temnikov.