The March 1941 ABC Conference of Britain, Canada, and the United States established Pacific operational areas that the Joint Chiefs of Staff reconfirmed in March 1942. The agreement gave the navy operational control over the central, southern, northern, and southeastern Pacific areas of operation; the army was responsible for the southwest Pacific. Further, the Pacific Military Council determined in March 1943 that all of the Pacific should be under the "strategic command" of Admiral Chester Nimitz, commander in chief, Pacific, although General Douglas MacArthur held overall command of the southwest Pacific. The actual boundaries had been established earlier in Joint Chiefs of Staff directives of 4 April 1942 to MacArthur and Nimitz that outlined the southeastern Pacific as everything east of a line drawn from the Mexico-Guatemala border to the mid-Pacific near Clipperton Island and then southward to the South Pole. To patrol this vast ocean area, Rear Admiral John F. Shafroth commanded a tiny force of three older light cruisers and several destroyers. As events played out, however, Shafroth's force proved more than sufficient, given the lack of Japanese activity.
Concern between the Pearl Harbor attack and the Midway victory over the security of the Panama Canal did not reflect in the naval defenses initially allotted to the region. To protect not only the canal itself but also transiting shipping, the U.S. Army had capable forces, but only in the 10-mile-wide Panama Canal Zone. The various Latin American countries offered little in terms of genuine security, even after Mexico and Colombia declared war on the Axis powers in 1943. The navy provided only minimal resources for Rear Admiral Clifford E. Van Hook's Panama Canal Force, consisting of the elderly destroyers Borie, Barry, Tattnall, and Goff along with the gunboat Erie, 2 patrol craft, 2 small converted motor yachts, and 24 Catalina maritime patrol aircraft. Although a few Japanese submarines entered the area as part of the June 1942 Japanese naval offensive against Midway and the Aleutian Islands, they did no damage. However, German U-boats did tremendous destruction to shipping on the Caribbean side of the canal, including two sinkings just outside the eastern entrance. But, again, the Japanese threat, which might have included carrier strikes, a possibility envisioned in war plans prior to December 1941 (Rainbow 5), never materialized on the Pacific side. Nor did the large 5,200-ton Japanese submarines of the I-400 class carrying 3 bomber-seaplanes (fielded in late 1944 and clearly designed for operations against the U.S. west coast and the Panama Canal) ever deploy to the region as anticipated.
Despite the ultimate lack of a credible Japanese threat to American shipping in the southeastern Pacific, a fact not realized until later in the war, naval commanders in 1942 assigned whatever escort assets were available to open-ocean vessels, particularly troop convoys transiting to the Central and Southwest Pacific Theaters and Pearl Harbor. In late January 1942, Shafroth's light cruisers Trenton and Concord and some destroyers escorted 2 large convoys from the canal through to Bora Bora with 4,500 men assigned to the construction of a new naval fueling station. At about the same time, the carrier Lexington and its assigned force escorted an 8-ship convoy carrying 20,000 troops through the southeastern Pacific (2 for Christmas Island, 2 for Canton Island, and 4 for New Caledonia).
In retrospect, the failure of the Imperial Japanese Navy to harass Allied shipping or to attempt even limited interdiction operations in the Southeastern Pacific represented a tremendous missed strategic opportunity. Although such a southeastern Pacific campaign would likely not have changed the eventual outcome of the war, it certainly would have mitigated Allied pressure in other Pacific areas of operation and complicated thrusts against the Japanese defensive perimeter.
Stanley D. M. Carpenter
Dull, Paul S. A Battle History of the Imperial Japanese Navy, 1941–45. Annapolis, MD: Naval Institute Press, 1978.; Morison, Samuel Eliot. History of United States Naval Operations in World War II. Vol. 5, The Struggle for Guadalcanal, August 1942–February 1943. Boston: Little, Brown, 1949.; Morison, Samuel Eliot. The Two-Ocean War: A Short History of the United States Navy in the Second World War. Boston: Little, Brown, 1963.; Van der Vat, Dan. The Pacific Campaign: The U.S.-Japanese Naval War 1941–1945. New York: Touchstone, 1991.