Find-a-Grave notesCivil War Union Army Officer. Entered the Civil War in January 1862 as Captain and commander of the 6th Battery, Maine Light Artillery, which he commanded at the Battles of Second Bull Run, Antietam, and Fredericksburg. Promoted from Captain to Lieutenant Colonel, he assumed command of the 1st Volunteer Artillery Brigade in the Army of the Potomac's Artillery Reserve. Led his command in the Battles of Chancellorsville, Gettysburg, and Mine Run. His performance on the 2nd Day of Gettysburg is considered his finest hour, and is what he is mainly remembered for. On that day he posted the cannons of his brigade along the Wheatfield Road to support the III Corps line that extended to the Peach Orchard and Emmitsburg Road. When the Confederates from General James Longstreet's Corps attacked and smashed the III Corps line, his 4 batteries fought hard until they were threatened by the Rebels, and were ordered by Colonel McGilvery to retreat to Cemetery Ridge. When he saw a huge hole in the Union line there, he ordered the 9th Massachusetts Battery to make a heroic, unsupported stand in front of the Trostle House while he scrapped together a defense on the Ridge. Colonel McGilvery then formed a line along the Plum Run (located in front of the present day Pennsylvania Monument) with time bought by the Massachusetts Battery, and he was able to hold off the Confederates until II Corps Infantry reinforcements were rushed to the area. This defense helped save the Union Army, and he was greatly lauded for his performance by his superiors. On the Third Day of the Battle his line of artillery helped destroy the celebrated Pickett's Charge. He continued to command the 1st Volunteer Artillery Brigade up to May 1864, when he was detailed to command the Army of the Potomac' ammunition and artillery train during the Overland Campaign. On August 9, 1864 he was named Chief of Artillery for the X Corps. At the Battle of Deep Bottom, Virginia (August 16, 1864) he sustained a slight wound to one of his fingers. He ignored this wound, and continued with his duties until an infection caused the need for the injured finger to be amputated. On September 2, 1864 in Petersburg, Virginia, he died suddenly during the surgery from the effects of chloroform. Today in the Gettysburg National Military Park an avenue is named "McGilvery Artillery Avenue" in honor of him and his command.