Soldier.
Leary, a resident of Boston, joined the Ninth Regiment of the Massachusetts Volunteer Infantry in June 1861, at the age of 22. The regiment, composed almost entirely of men of Irish birth, fought in many Civil War battles between 1861 and 1864 including: Second Battle of Bull Run, Antietam, Fredericksburg, Gettysburg, Chancellorsville, the Wilderness Campaign, Spotsylvania, and the Siege of Petersburg and was part of the pursuit of Lee's Army of Northern Virginia at Appomattox. Leary received final discharge papers from the Army on July 11, 1865.
From the description of Michael H. Leary letters, 1861-1863. (Boston College). WorldCat record id: 32061793