War Department

American  

noun

U.S. History.

1. the department of the federal government that, from 1789 until 1947, was responsible for defense and the military establishment: in 1947 it became the Department of the Army, which became part of the Department of Defense when it was established in 1949.

---

Example Sentences

President Abraham Lincoln spent many evenings in the War Department telegraph office reading dispatches and issuing orders.

From The Wall Street Journal • Apr. 26, 2026

“The first sinking of an enemy ship by a torpedo since World War II. Like in that war back when we were still the War Department, we are fighting to win.”

From Barron's • Mar. 6, 2026

The Pentagon - which oversees the US armed services - is the successor to the War Department, which was first established as a cabinet-level agency in 1789 and existed until 1947.

From BBC • Sep. 4, 2025

As he revealed in his 2013 documentary memoir “Ain’t Misbehavin,” he began his career as an actor, playing, ironically, a member of the Hitler Youth in Frank Capra’s 1942 War Department film “Prelude to War.”

From Los Angeles Times • May 29, 2025

Men ran or galloped to the White House, the War Department, and the homes of cabinet officers.

From "Chasing Lincoln's Killer" by James L. Swanson