Corporal O'Connell was born on September 9, 1895 in Ireland.
He served in Company D of the 101sth Infantry Regiment, 26th “Yankee” Infantry Division during the First World War. On July 23, 1918 he was awarded the Distinguished Service Cross posthumously for extraordinary heroism.
He Is buried next to his brother, Corporal Martin O’Connell who also fought in WW1 with the 163rd Infantry Regiment, 41st Infantry Division in France. Martin survived the war, but his son was killed on Iwo Jima during WW2.
From an American Legion Article:
The 26th Yankee Division went into battle on July 15, 1918 to help blunt the German Champagne-Marne offensive. (Second Battle of the Marne)"
The Allied counterattacked on July 18. The 26th Division deployed just west of Chateau-Thierry. The Division attacked east-northeast with the 52nd Brigade on the left of the 51st Brigade (including the 101st Infantry on the right.) Initial progress was limited; by July 21, the Division had advanced roughly four miles. Before it lay the towns of Epieds on the left and Trugny on the right. On July 22, the 101st Infantry was moved from reserve into the line."
"On July 23, the 101st pushed past Trugny towards the woods to the east known as the Bois de Trugny. Officers called for volunteers to locate the enemy machineguns hidden in the woods that were preventing further advance," said the letter from the U.S. Army Center of Military History"
Quoting the military report, "From Company D, 101st Battalion, Sgt. Simeon L. Nickerson, Cpl. Michael J. O'Connell and Pvt. Thomas A. Ryan volunteered."
They advanced across a wheat field with little or no cover, located a machinegun position, and attempted to attack, but were struck down, either by the targeted machinegun or a second machinegun, or snipers (accounts vary).
The report continues, "Their commander recommended them for the Distinguished Service Cross, which was awarded posthumously. The citation noted, the heroic self-sacrifice of these three men saved lives of many of their comrades who would have been killed had the company attempted to advance as whole."
DSC Citation: The President of the United States of America, authorized by Act of Congress, July 9, 1918, takes pride in presenting the Distinguished Service Cross (Posthumously) to Corporal Michael J. O’Connell, United States Army, for extraordinary heroism in action while serving with Company D, 101st Infantry Regiment, 26th Division, A.E.F., near Epieds, France, 23 July 1918. Sergeant Nickerson, Corporal M. J. O'Connell, and Private Thomas Ryan volunteered to cross an open field in front of their company, in order to ascertain the location of enemy machine guns. While engaged in this courageous enterprise they were shot and killed. The heroic self-sacrifice of these three men saved the lives of many of their comrades who would have been killed had the company attempted to make the advance as a whole.

Corporal O'Connell is also remembered on the 26th Division Tablets at the Belleau Church in France (See 26th Division Tablets, Site Belleau Church for more on this memorial.).