Engaging the enemy again near Spottsylvania on May 18, Harris and the 148th Pennsylvania then fought in the Battle of Cold Harbor on June 3. After the regiment buried the last of its dead, they withdrew to Wilcox Landing and, beginning June 16, participated with other Union troops in the Siege of Petersburg. Engaged in the Battle of Hare House on June 16 and the fighting at Fort Stedman against the second line of Confederate General Robert E. Lee, they also skirmished with the enemy three days later near Williams House. On July 27, 1864, they captured a Confederate artillery battery in the First Battle of Deep Bottom, fought in the Battle of the Crater (July 30), fought in the Second Battle of Deep Bottom (August 14-20), helped to destroy the Weldon Railroad (August 22), fought in the Second Battle of Ream's Station (August 25), and then skirmished off and on with the enemy while stationed in and around Forts Stedman, Rice and Morton during the months of September and October. On December 1, Harris and his fellow B Company soldiers were assigned with those from the 148th Pennsylvania's D, E, H, and I companies to garrison Fort Gregg. Five days later, on December 6, the U.S. Medal of Honor was presented to Harris personally by Major-General George Meade, commanding officer of the U.S. Army of the Potomac, during a formal ceremony in front of the 148th Pennsylvania and other Union troops near Petersburg, Virginia at the Peebles' House, which had been taken over by the Union for use as the headquarters of the U.S. Second Army Corps.