Among his classmates included several general officers of the future, such as Charles Gerhardt, Ulysses G. McAlexander, Ernest Hinds, Nathaniel Fish McClure, William Weigel, Charles S. Farnsworth, James Theodore Dean, Mark L. Hersey, Herman Hall, Frank Herman Albright, Marcus Daniel Cronin, George Owen Squier, Thomas Grafton Hanson, George Washington Gatchell, Alexander Lucian Dade and Edmund Wittenmyer.

[1] The division was a recently activated National Guard formation and was commanded at the time by Major General William Abram Mann.

The division began to depart for service overseas on the Western Front in October, arriving in France in early November.

Major General William M. Wright, commanding the nearby 89th Division, describes in his diary that MacArthur's troops could approach Hill 288 and Châtillon-sous-les-Côtes using the forest as cover and took the objective, while Lenihan's brigade was stopped by enemy resistance before they could take the objectives in the Landres-et-Saint-Georges area, sustaining heavy casualties.

[2] Summerall ordered Major General Charles T. Menoher, the 42nd's commander since the previous December, to relieve Lenihan, which he did on 17 October 1918, being replaced by a much younger man, Colonel Henry J. Reilly.