Page 124 - Historical Study of Yerba Buena Island, Treasure Island and Their Buildings

Rear Admiral Hugo R. Osterhaus, USN Retired, had joined the Navy in 1900. After having
served in World War I and as Commanding Officer of Mare Island Naval Shipyard twice, the
Rear Admiral retired. He again answered the call of his country when he came out of retirement
and was reactivated as the Commander of the TADCEN and the United States Navy (USN)
"Patrol Force". In spite of generally peaceful conditions on the West Coast, a USN "Patrol
Force" was now in full operation because there were rumors of German submarine "Wolf Packs"
attacking ships. Osterhaus and his mighty "Patrol Force" moved to Treasure Island on June 12,
1941.

The first major use of the Island by TADCEN was for training, inshore and offshore patrol,
coastal lookouts, mine forces, and net defenses. The function of the base was to provide support
for the Local Defense Forces. The installation also provided foul weather refuge for small patrol
craft both inharbor and offshore, supplied small craft with stores and food, made minor ship
repairs, and provided Quarters and recreational facilities for crews while in port for extended
periods. With TADCEN and the Patrol Force located on the island, slowly but steadily, the
deserted fairgrounds were converted to a naval station. Barracks were set up in what was known
as the Hall of Western States during the days of the Exposition. A galley was commissioned in
what had been the Federal Building. Fishing boats were converted to mine sweepers, and yachts
to patrol craft. A local Harbor Defense School began the practical training of naval officers and
a Radio Materiel School was established. The "Sick Bay" opened in July of 1941 with four
doctors, one dentist, and nineteen corpsmen whose duties included sanitation, as well as the
usual treating of the sick crew.

When Japan attacked Pearl Harbor, the nation's pnontles quickly changed. Although the
Germans were still on a rampage throughout Europe, Japan had attacked US soil. This caused
the United States to take Japan seriously. The US immediately shifted its industrial and military
systems into high gear. Japan's attack on Pearl Harbor did not alter the United States' war
policies. Under the so-called "Hitler First Method", the war in Europe continued to be top
priority, while the war in the Pacific came second. -

The day after the attack on Pearl Harbor, the Port of the Tradewinds was jammed with fishing
vessels, small craft, and luxury yachts released by their owners for emergency Naval Patrol
service. Coastal tankers were considered targets for enemy submarines. Merchant vessels
demanded gun crews and escorts. Until the arrival of four destroyers from San Diego, a grey-
painted fishing vessel having good lines, fair speed, a couple of gun mounts, and a Navy crew
served as that escort when the ships sailed through the huge submarine net which spanned the
Golden Gate channel guarding the Harbor.

Twelve days after the Japanese attack on Pearl Harbor, the Armed Guard Center - Pacific came
into existence as a command under TADCEN. The pre-war Navy could not envision the
magnitude of the task ahead for the Armed Guard. This is depicted in an exerpt from the
directive authorizing the establishment of the Center. The directive read: "It is contemplated
that the administrative load will not exceed a maximum of one hundred fifty officers and one
thousand two hundred men both at the Center and on duty at sea." Of course, this manpower
count was rapidly exceeded. The Navy armed every merchant ship and transport vessel sailing
from the US shore due west with an Armed Guard crew and at least one gun, usually a five inch,
38 caliber, dual purpose gun. It was the duty of the Armed Guardsmen to protect their ships
from the attacking enemy planes and submarines. The first crew was assigned to duty aboard a

2-20 Historical Study ofYerba Buena Island, September 1, 1995
Treasure Island, and their Buildings