Baker wanted the brigade to represent and give credit to California in the Federal army.

[1] After Baker's death October 21, 1861 at the Battle of Ball's Bluff, Pennsylvania reclaimed the regiments as its own.

At the Battle of Antietam, the regiment participated in the attack on the West Woods, being routed along with much of the rest of the division.

On the evening of the 2nd, it helped defeat Confederate Brigade General Ambrose R. Wright's attack, advancing just over the stone wall.

During Pickett's Charge, its position served as a rallying point for the left wing of the 71st and two companies of the 106th Pennsylvania, which had been driven back.