On August 22, 1861, Connor was commissioned as
lieutenant colonel and second-in-command of the
7th Maine Infantry. He took part in the Union's
Peninsula campaign of March to July 1862, as well as the
Battle of Antietam in September 1862 and the
Battle of Fredericksburg the following December. Connor was wounded at Fredericksburg, but remained with his regiment, and at times served as its acting commander. Connor was also with the 7th Maine during its participation in the July 1863
Battle of Gettysburg. In January 1864, Connor was promoted to
colonel and assigned to command the
19th Maine Infantry. Because his brigade commander frequently acted as a division commander, Connor acted as commander of 1st Brigade, 2nd Division,
II Corps. He led his regiment during the May 1864
Battle of the Wilderness, at which he was severely wounded when a bullet shattered his thigh bone. Connor spent more than a year recovering in Washington, D.C. hospitals and was bedridden for much of the time. While he was hospitalized, Maine newspapers incorrectly reported that he had died in combat; corrections were issued several days later. In June 1864, he was promoted to
brigadier general, but his convalescence prevented him from actively exercising the responsibilities of the rank. He returned to Maine in August 1865 and was mustered out of the army in April 1866. After the war, Connor remained active in the
Military Order of the Loyal Legion of the United States,
Grand Army of the Republic, Society of the
Army of the Potomac, and Society of American Wars. From 1866 to 1867, Connor was president of the Maine State Soldiers' and Sailors' Union, a fraternal advocacy organization for Civil War veterans. He was a sought after orator, and frequently gave speeches at the dedications of memorials and monuments to Maine's wartime service. ==Continued career==