FORWARD OPERATING BASE MAREZ, Iraq  When the 101st Airborne Division captured this base back in 2003, an American tank blasted the turret off a T-72 tank, catapulting it into the side of St. Elijah’s Monastery.

The force buckled a wall of mortar and stone that had stood for more than 1,000 years here in one of the earliest redoubts of Christianity. Such is the tragedy of war.

The division then made the site a garrison and painted its emblem on the stucco above the low door to the monastery’s chapel. The insignia remained there until a chaplain contemplated the righteousness of having “Screaming Eagles” adorn a house of God.

Image Maj. Jeffrey Whorton, a Roman Catholic chaplain, celebrating Mass at St. Elijah’s Monastery near Mosul in northern Iraq. Credit... Eros Hoagland for The New York Times

“That’s not right,” the chaplain said, as the story goes.

Thus began the accidental American stewardship of St. Elijah’s, an ancient site of Christian worship and martyrdom now stuck in the middle of a sprawling military base just south of Mosul, in northern Iraq.