Attached to the Provisional Brigade, Defenses of Bermuda Hundred, U.S. Army of the James, from September to November 1864, Hoffman and his fellow 208th Pennsylvanians performed fatigue and picket duties in the vicinity of Bermuda Hundred, Virginia as part of the operations related to the Siege of Richmond. Reassigned to the Provisional Brigade, 9th U.S. Army Corps' Army of the Potomac for December of that year, they supported the Union's Weldon Railroad Expedition. Reassigned to the 9th Corps' 1st Brigade, 3rd Division, they then fought in the battles of Dabney's Mill and Hatcher's Run (February 5–7, 1865), Fort Stedman (March 25), and in the Appomattox Campaign (March 28 to April 9). During the opening days of this latter campaign, Hoffman was detailed, on April 1, as acting engineer officer with the 3rd Division, 9th U.S. Army Corps. The next day, he performed the act of "extraordinary heroism" for which he would later be awarded his nation's highest honor for valor, the U.S. Medal of Honor. Interviewed later in life, Hoffman described what happened that day: During the week that we were stationed at Steadman our division was ordered to capture Lee's works. I was detailed on General Hartranft's staff as engineer officer of the division. The troops were ordered out in the middle of the night and deployed inside our picket lines. When daylight began to show on the eastern horizon a signal gun was fired. This was the signal for the attack and our troops advanced to the fray. They rushed across the space between the two lines, tore down the obstructions, jumped into the moat from whence they scaled the walls of the fort, capturing four forts with twenty-five guns in a space of five minutes. We also captured a large number of prisoners. The rebels made a great effort to retake the forts, making numerous charges, but we succeeded in holding them back during the entire day. Sometime during the afternoon I was sent out by General Hartranft to the commanding officer of the second brigade to ascertain if it were possible for him to hold the forts captured. Just as I came to the forts it happened that my own regiment, the Two Hundred and Eighth was deployed.... When I was but a short distance away I heard the lieutenant-colonel of my regiment call to the men to retreat, and that they were being surrounded. Presently