William Pywell was born in in Baltimore, Maryland, on 9th June, 1843. He moved to Washington where he found employment as a photographer at a studio owned by Matthew Brady. By this time Brady's eyesight had deteriorated and he received his training from Alexander Gardner.
On the outbreak of the American Civil War there was a dramatic increase in work as soldiers wanted to be photographed in uniform before going to the front-line. The following officers were all photographed at the Matthew Brady Studio: Nathaniel Banks, Don Carlos Buell, Ambrose Burnside, Benjamin Butler, George Custer, David Farragut, John Gibbon, Winfield Hancock, Samuel Heintzelman, Joseph Hooker, Oliver Howard, David Hunter, John Logan, Irvin McDowell, George McClellan, James McPherson, George Meade, David Porter, William Rosecrans, John Schofield, William Sherman, Daniel Sickles, George Stoneman, Edwin Sumner, George Thomas, Emory Upton, James Wadsworth and Lew Wallace.
In July, 1861 Matthew Brady and Alfred Waud, an artist working for Harper's Weekly, travelled to the front-line and witnessed Bull Run, the first major battle of the war. The battle was a disaster for the Union Army and Brady came close to being captured by the enemy.
Soon after arriving back from the front Matthew Brady decided to make a photographic record of the American Civil War. He sent Pywell, Alexander Gardner, James Gardner, Timothy O'Sullivan, George Barnard, and seventeen other men to travel throughout the country taking photographs of the war. Each one had his own travelling darkroom so that that collodion plates could be processed on the spot.
After the war Pywell accompanied Alexander Gardner on the Kansas Expedition before establishing his own studio in Washington. He also went with George Custer as the official photographer of the Yellowstone Expedition. William Pywell died in 1887.