 Leeb took part in the invasion of Poland, with his XI Corps attacking towards Warsaw.He initially reported to Walther von Reichenau of the 10th Army, before his unit formed the left wing of Reichenau's drive towards Łódź.Later, his unit was transferred to Johannes Blaskowitz's 8th Army in its attack from the east-central region of Germany into west-central Poland, before sweeping on towards Warsaw.