Which Union general took command of the I Corps after John Reynolds was killed?

Abner Doubleday took command of the Union I Corps after Major General John Reynolds was killed near Gettysburg on July 1, 1863. Reynolds, commander of the Army of the Potomac’s left wing and the I Corps, was directing the opening Union deployment when he was fatally shot near Herbst Woods.

Doubleday, the I Corps’ senior division commander on the field, assumed command as the battle intensified. He helped organize the corps’ resistance on McPherson Ridge and Seminary Ridge against attacks by Confederate forces under A. P. Hill. The I Corps eventually retreated through Gettysburg with the XI Corps, then regrouped on Cemetery Hill and Cemetery Ridge.

The sequence can be confusing because Major General Winfield Scott Hancock arrived later and was sent by George Meade to take command of the Union forces at Gettysburg. Hancock did not immediately replace Doubleday as commander of the I Corps; Doubleday remained in that role through the first day. He was relieved of corps command soon afterward, but his battlefield succession after Reynolds’s death was clear.