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.

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Example Sentences

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War Department

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 Department of Defense, now called the War Department, is investing directly in companies, demanding greater production and new technology.

From Barron's ● Jan. 14, 2026

In the end, the president will get his War Department.

From Salon ● Sep. 11, 2025

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

Lafayette Baker, the notorious detective and War Department agent—and a favorite of Stanton’s—had been in Washington since April 16.

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