After the Battle of Moscow, the OKH commander Field marshal Walther von Brauchitsch was removed from office, and Hitler appointed himself as Commander-in-Chief of the Army.

After a major crisis developed in the Battle of Moscow, von Brauchitsch was dismissed (partly because of his failing health), and Hitler appointed himself as head of the OKH.

This enabled Hitler to declare that only he had complete awareness of Germany's strategic situation, should any general request a transfer of resources between the Russian front and another theatre of operations.

[1] Although both OKW and OKH were headquartered in the Maybach complex in Nazi Germany, the functional and operational independence of both establishments were not lost on the respective staff during their tenure.

On 28 April 1945 (two days before his suicide), Hitler formally subordinated OKH to OKW, giving the latter command of forces on the Eastern Front.