The Cotton Bale Bridge of Grant's Vicksburg Campaign

Today I posted a little item on civilwartalks.com's forum for Vicksburg (I hope--this is my first posting there. 

The Cotton Bale Bridge of Grant's Vicksburg Campaign​

After the battle of Champion's Hill drove most of the Confederates involved back into Vicksburg on May 16, 1863, they attempted unsuccessfully to make a stand on the Big Black River northeast of the doomed city. As they retreated back into Vicksburg, some of the victorious Federals resorted to an unusual means to pursue—a bridge built of cotton bales.

The chief engineer of McPherson's corps, Capt. Andrew Hickenlooper, arrived at the Big Black about 2 p.m. on May 17. With the help of the chief engineer of Logan's division, Capt. Stewart R. Tresilian, Hickenlooper began construction of a cotton bridge around dark. The bridge had a timber frame filled with 47 cotton bales and covered with boards from a nearby cotton gin. Hickenlooper and Tresilian had both distinguished themselves at the battle of Shiloh. Hickenlooper won praise commanding the 5th Ohio Independent Battery and Tresilian earned the praise of his previous division commander for half a dozen bullet "unsurpassed activity and daring throughout the battle," in which Tresilian suffered six bullet wounds.

By 8:00 a.m. on May 18, their bridge stood 110 feet long by 10 feet wide in water 30 feet deep. At that time, Quinby's division of McPherson's corps advanced over the bridge. "I witnessed the crossing of the division, and found that the 20-pounder Parrott sunk the structure only 14 inches, leaving an excess of buoyancy of 16 inches," wrote Tresilian. "I am of the opinion that the cotton bridge is equal, if not superior, to the pontoon, being much smaller and easily constructed." Theodore Davis, an illustrator for Harper's Weekly, recalled, "The buoyancy of a 500-pound bale of cotton is quite 400 pounds, and serviceable for eight days."

Cotton Bale Pontoon Bridge over the Big Black River
Sketch and Description by Theodore Davis, Harper's Weekly, June 27, 1863​

Sources
OR 10, pt. 1.
OR 24, pt. 2.
"Death of Col. Tresillian," The Monmouth (NJ) Inquirer, Jan. 14, 1869, p. 2, col. 2.
Harper's Weekly, June 27, 1863.