Lt. Gen. Charles Costanza was relieved of command of V Corps in August 2026, about two months before he was set to hand over the post. Brig. Gen. John Mountford will serve as acting commander while the Army has not said why Costanza was removed.
The timing matters because Costanza’s change of command with Maj. Gen. Thomas Feltey had been planned for October, meaning the removal cut short what was already a scheduled transition. Costanza had led V Corps since April 2024.
V Corps is the Army’s forward-deployed headquarters in Poland and its command reaches across NATO’s eastern flank. Headquartered in Poznan, Poland, with a separate stateside command post at Fort Knox in Kentucky, it was reactivated in Poland in 2020 and later became the Army’s first permanent garrison in Poland.
The corps has also sat at the center of the Army’s work in eastern Europe, including Operation Atlantic Resolve, Project Flytrap and Transforming in Contact. It oversees the 2nd Cavalry Regiment in Vilseck, the 41st Field Artillery Brigade in Grafenwoehr and the 12th Combat Aviation Brigade in Ansbach.
The reason for Costanza’s relief remains undisclosed. An Army spokesperson said the matter had been referred to the appropriate authority in accordance with Army regulations, leaving the removal hanging over a command that sits on one of the military’s most sensitive fronts.
That silence is the sharp edge of the story. The Army moved quickly enough to replace Costanza but not to explain the decision, and that gap matters at a moment when Defense Secretary Pete Hegseth has overseen the removal of several senior military leaders and pushed to reduce the number of general and flag officers. The Pentagon also launched a review of the U.S. military mission in Europe last month, a step that could lead to a wider overhaul as the U.S. military presence there has already been reduced over the past year.
For now, Mountford inherits a command built for continuity but suddenly marked by uncertainty. The next answer that matters is the one the Army has not given: what led to Costanza’s removal in the first place.
