An eye-witness thus describes the famous passage of the Lech by Gustavus Adolphus:
“Resolved to view the situation of the enemy, his majesty went out the 2nd of April (1632) with a strong body of horse, which I had the honor to command. We marched as near as we could to the bank of the river, not to be too much exposed to the enemy’s cannon; and having gained a height where the whole course of the river might be seen, we drew up and the king alighted and examined every reach and turning of the river with his glass. Toward the north, he found the river fetching a long reach and doubling short upon itself. ‘There is the point will do our business,’ says the king, ‘and if the ground be good, we will pass there, though Tilly do his worst’.”
He immediately ordered a small party of horse to bring him word how high the bank was on each side and at the point, “and he shall have fifty dollars” says the king, “who will tell me how deep the water is.”
… The depth and breadths of the stream having been ascertained, and the bank on our side being ten to twelve feet higher than the other and of a hard gravel, the king resolved to cross there; and himself gave directions for such a bridge as I believe never army passed before nor since.
The bridge was loose plank placed upon large tressels as bricklayers raise a scaffold to build a wall. The tressels were made some higher and some lower to answer to the river as it grew deeper or shallower; and all was framed and fitted before any attempt was made to cross.
At night, April 4th the king posted about 2,000 men near the point and ordered them to throw up trenches on either side and quite around it; within which at each end the king placed a battery of six pieces and six cannon at the point, two guns in front and two at each side. By daylight, all the batteries were finished, the trenches filled with musketeers and all the bridge equipment at hand in readiness for use. To conceal this work the king had fired all night at other places along the river.
At daylight, the Imperialists discovered the king’s design, when it was too late to prevent it. The musketeers and the batteries made such continual fire that the other bank twelve feet below was too hot for the Imperialists; whereupon old Tilly to be ready for the king on his coming over on his bridge, fell to work and raised a twenty-gun battery right against the point and a breast-work as near the river as he could to cover his men; thinking that when the King should build his bridge, he might easily beat it down with his cannon.
But the King had doubly prevented him; first by laying his bridge so low that none of Tilly’s shot could hurt it, for the bridge lay not above half a foot above the water’s edge; and the angle of the river secured it against the batteries on the other side, while the continual fire beat the Imperialists from those places where they had no works to cover them.