The Custom of the Army is a novella in the Lord John Series by Diana Gabaldon. It was originally published in 2010 in the anthology Warriors (Volume 1), which was edited by George R. R. Martin and Gardner Dozois.
On May 21, 2012, "The Custom of the Army" was published as a standalone ebook. It is also included in a book-length collection of Gabaldon's short stories, A Trail of Fire.
In 1759, the morning after a duel in which the other participant is killed, Lord John Grey is presented with a series of letters accusing him of murder, a demand for satisfaction for compromising the honor of the lady over whom the duel was fought, a plea from the lady herself to do 'something', a promotion to Lt. Colonel as a result of events that occurred in Brotherhood of the Blade, and a summons to represent a companion officer who is being court martialled in Canada. Considering the latter to be the least of the evils he has been presented with before breakfast, Grey departs for North America.
In Louisbourg, he joins General Wolfe's forces during their three month siege of Quebec, but the General is currently not available. During his stay Lord John discovers his cousin by marriage, Malcolm Stubbs, in questionable living arrangements, with an illegitimate child; however, he is unable to confront Capt. Stubbs who is currently on a scouting mission. Meanwhile, his friend and former lover Charlie is under house arrest and in failing health, awaiting the court martial that has not yet been scheduled due to the ongoing siege of Quebec. Grey passes the time he must wait on a fishing trip with Manoke, an Indian guide.
Upon his return in September, Grey finds both Wolfe and Stubbs have both returned as well. Grey violently objects to Stubbs dishonorable behavior, and briefly considers, but refrains from, killing him.
Wolfe invites Grey, an artillery officer with experience with Highlanders, to participate in the daring night-time landing of cannon along the St. Lawrence River, through French sentries, and up the steep cliffs. After scaling the cliffs with the cannon crews, Grey is with the 78th Fraser Highlanders during the Battle of the Plains of Abraham which takes place hours later.
Capt. Stubbs is critically injured in the battle, and Grey with the assistance of an other officer carries him back to the medics, which saves his life, but not his leg. After the battle, Stubbs is shipped back to England on disability and Grey returns to find both his friend Charlie and the mother of Stubbs' illegitimate son dead of smallpox. The infant's grandmother sells the child to Grey. He takes the baby to a Catholic orphanage, leaving him with an annual stipend and naming him 'John Cinnamon'.