Under Capt. Samuel E. Barrett and Lieut. Israel P. Rumsey, U.S. Battery B served four 6-pounder guns and two 12-pounder howitzers in this position from the morning of May 22 to the evening of May 26, when it went with the force under command of Gen. Blair on the expedition to Mechanicsburg. The battery did not return to the investment line but was attached to Mower's Brigade and engaged at Richmond, Louisiana, June 15. It served two of its pieces, by successive details, on the peninsula opposite Vicksburg from June 23 to the end of the siege, July 4, 1863. Aggregate reported casualties in the battery during the campaign and siege were 2 killed and 2 wounded, a total of 4.