USS Mount McKinley (AGC-7)

May 2006 Cover of the Month

Operation Crossroads

2006 is the 40th anniversary of the nuclear weapons tests at Bikini Atoll in the Marshall Islands. The tests were given the name of Operation Crossroads. Two tests were performed; Operation Able was an air burst occurring on July 1, Operation Baker an underwater detonation on July 25. These tests would study the effects of nuclear weapons on ships and equipment. The US Navy assembled more than 90 ships in Bikini Lagoon to be used as targets. This target fleet consisted of older and surplus US Navy carriers, battleships, cruisers, destroyers and submarines, three captured German and Japanese ships, and a large number of auxiliary and amphibious vessels. Military equipment was installed on some of the ships as well as amphibious craft that were berthed at Bikini Island. Technical experiments were also conducted to study nuclear weapon explosion phenomena.

The Able test was exploded July 1 at an altitude of 520 feet however it was almost 2000 feet of target and as a result, only 5 ships were sunk and the test did not meet all of the objectives. The Baker test took place on July 25 and sunk 8 ships and damaged many more, the weapon being exploded 90 feet underwater. Most of the ships were too radioactive to reboard for several weeks. Among the ships that were sunk was the aircraft carrier USS Saratoga.

The US Navy was organized as Joint Task Force One for the tests, the USS McKinley served as the flagship. The Task Force was divided into 8 Task Groups: 1.1 Technical Group, 1.2 Target Vessel Group, 1.3 Transport Group, 1.4 Army Ground Group, 1.5 Army Air Group, 1.6 Navy Air Group, 1.7 Destroyer Surface Patrol Group and 1.8 Service Group. The support fleet of more than 150 ships provided quarters, experimental stations, and workshops for most of the 42,000 men (more than 37,000 of whom were Navy personnel) of Joint Task Force One. Additional personnel were located on nearby atolls such as Eniwetok and Kwajalein. The islands of the Bikini Atoll were used primarily as recreation and instrumentation sites. Before the first test, personnel were evacuated from the target fleet and Bikini Atoll.

The cover this month carries the corner card of the flagship USS McKinley. The cancel marks the date of the Able Test, July 1. A form letter enclosed, dated July 1, 1946, notes:

“Greetings from Bikini: This letter is being addressed and mailed to you on ABLE Day, the day on which the atomic bomb was dropped in the first of the tests known as Operation Crossroads. All mail passing through the Mobile Fleet Post Office, Bikini Atoll, Marshall Islands, (LST-861) on this day bears a special ABLE Day cancellation with the words “Atomic Test Bikini Atoll” in the killer bars and with the date of the test appearing in the cancellation. It is estimated that approximately two hundred thousand (200,000) letters will be cancelled this day with this special postmark. The cachet will be placed in the archives of the Chief of Naval Operations, Postal Affairs Section, for reference in authenticating the postmark for philatelists and collectors. It is believed that such a souvenir of this occasion may be of interest to you. Sincerely, W. H. P. Blandy, Vice Admiral, US Navy, Commander Joint Task Force One.”