On 14 September 1959, the keel of USS ETHAN ALLEN (SSBN-608) was laid down at General Dynamics Electric Boat in Groton, CT. Although she was the sixth of the “41 for Freedom” ballistic-missile submarines, she was the first specifically designed as such—the earlier GEORGE WASHINGTON-class BNs were built as variants on the design of a fast-attack boat, USS SKIPJACK (SSN-585). The result was the heaviest sub the U.S. had ever built: 6,900 tons on the surface. That may not seem like much when compared with the 18,000-ton ballistic behemoths that prowl the seas today, but at the time it was huge. ETHAN ALLEN was 1,000 tons heavier than USS TRITON (SSN-586), which was 37 feet longer, 1,500 tons heavier than GEORGE WASHINGTON, and 4,500 tons heavier than the average World-War-II sub.
In the fall of 1961, the Soviet Union, which had previously joined the U.S. in a moratorium on nuclear testing, broke the agreement in spectacular fashion by conducting 45 atomic-weapons tests in just 65 days, including one of a 63-megaton hydrogen bomb that still holds the record as the largest-ever nuclear explosion. The United States responded by planning FRIGATE BIRD, an operation meant to test the capabilities of the nuclear-armed POLARIS missiles carried by ETHAN ALLEN and her sister subs. Because ETHAN ALLEN was the newest sub, she got the call. Before leaving South Carolina for the test zone, four of her POLARIS missiles were fitted with tracking devices and command-destruct systems.
On 2 May, the sub rendezvoused with surface vessels about 1,500 miles northeast of Christmas Island and to the southeast of Hawaii. USS CARBONERO (SS-337) and USS MEDREGAL (SS-480) were stationed far from the main fleet, lurking at periscope depth just 25 miles from the target area. On 6 May, after days of planning and a morning fraught with weather problems and technical headaches, ETHAN ALLEN, submerged at firing depth, finally launched a POLARIS just after two in the afternoon. When the missile cleared the water, the range safety ship locked on to its tracking beacons and informed the two submarines and observation aircraft that it would arrive at the burst point, about 1,100 miles away, in 12-13 minutes. Sure enough, just over ten minutes later observers witnessed the blinding flash that was the missile exploding harmlessly at 11,000 feet.
“If any adversary had doubted the credibility of the sea-borne leg of the nation’s nuclear triad before, [FRIGATE BIRD] certainly eliminated any remaining uncertainty,” Edward C. Whitman wrote in Undersea Warfare in the fall of 2004. “In vectoring Ethan Allen so quickly to the Pacific and demonstrating convincingly that a front-line submarine…could execute its strategic mission on short notice, the Submarine Force struck a solid blow for nuclear deterrence. A full-system, strategic-weapon test had never been done before, and because the Limited Test Ban Treaty among the United States, the Soviet Union, and the United Kingdom ended atmospheric testing by those three nations only a year later, it was never done again.” In this first and only test, ETHAN ALLEN placed the missile just 1.25 miles from the initial aim point.
Seen through the periscope of USS CARBONERO (SS-337), submerged 25 miles from the aim point, this illustration shows FRIGATE BIRD’s mushroom-shaped cloud boiling skyward from its original burst altitude of 11,000 feet. The range clock at the upper right indicates 1433, which was the local time at the launching point. (Local time at the aim point was one hour earlier.)
