North Anna River, Virginia. Pontoon bridges constructed by the 50th New York Volunteer Engineers. Where a portion of the 2nd Corps under General Hancock crossed, May 23, 1864 (Timothy O'Sullivan/ Library of Congress)

North Anna River, Virginia. Pontoon bridges constructed by the 50th New York Volunteer Engineers. Where a portion of the 2nd Corps under General Hancock crossed, May 23, 1864 (Timothy O’Sullivan/ Library of Congress)