Leder was initially stationed at the Naval Reserve Aviation Base in Minneapolis, Minnesota.
He became an aviation cadet on October 1, 1941 and attended flight training at Naval Air Station Pensacola.
He was commissioned an ensign on May 15, 1942.
On May 18 of that same year, he married Kathryn Sylvia Loran before being transferred to Aircraft Carrier Training Group NAS San Diego in June.

In August of 1942, he joined Fighting Squadron 10 (VF-10) before being shipped out to the Pacific Theater.

Leder flew as a member of what was known as the Cactus Air Force.
He was part of a large assembly of allied air power assigned to the Solomon Islands in support of the Guadalcanal campaign.
He was stationed on the USS Enterprise during the Battle of Santa Cruz Islands and flew multiple air combat patrol missions in defense of his carrier group against enemy Japanese forces.

In his first air combat engagement on October 26th, 1942, he shot down at least one enemy dive bomber in defense of the Enterprise.

On November 13, 1942, he was part of a four plane flight on combat patrol over the Enterprise that intercepted and shot down a Japanese bomber shadowing the task force.

Later on January 30, 1943, he shot down a torpedo bomber attempting to attack the cruiser USS Chicago as it sat damaged near Rennell Island.
Leder was initially stationed at the Naval Reserve Aviation Base in Minneapolis, Minnesota. He became an aviation cadet on October 1, 1941 and attended flight training at Naval Air Station Pensacola. He was commissioned an ensign on May 15, 1942. On May 18 of that same year, he married Kathryn Sylvia Loran before being transferred to Aircraft Carrier Training Group NAS San Diego in June. 
In August of 1942, he joined Fighting Squadron 10 (VF-10) before being shipped out to the Pacific Theater.
Leder flew as a member of what was known as the Cactus Air Force. He was part of a large assembly of allied air power assigned to the Solomon Islands in support of the Guadalcanal campaign. He was stationed on the USS Enterprise during the Battle of Santa Cruz Islands and flew multiple air combat patrol missions in defense of his carrier group against enemy Japanese forces.
In his first air combat engagement on October 26th, 1942, he shot down at least one enemy dive bomber in defense of the Enterprise. 
On November 13, 1942, he was part of a four plane flight on combat patrol over the Enterprise that intercepted and shot down a Japanese bomber shadowing the task force. 
Later on January 30, 1943, he shot down a torpedo bomber attempting to attack the cruiser USS Chicago as it sat damaged near Rennell Island.
William H. Leder