Operation Grapple, and operations Grapple X, Grapple Y and Grapple Z, were the names of British nuclear tests of the hydrogen bomb.

Operation Grapple, and operations Grapple X, Grapple Y and Grapple Z, were the names of British nuclear tests of the hydrogen bomb. They were held 1956 – 1958 at Malden Island and Christmas Island in the central Pacific Ocean. Nine nuclear detonations took place during the trials, resulting in Britain becoming a thermonuclear power. All of the bombs were exploded in the air, rather than on the surface, to reduce the effects of fallout.

Untested and unproven thermonuclear designs being developed at Britain’s nuclear weapons research establishment, the AWRE, required proof testing, so Grapple was conducted as a massive tri-service operation, the largest of its kind since World War II. Initial preparation for the operation, including establishing necessary infrastructure on Christmas Island, began at the end of May 1956. About 1,200 civilian and military personnel were stationed on Christmas Island during that year.

The following ships of the Royal Fleet Auxiliary were deployed to Christmas Island in support of these operations: –

* ship renamed RFA Reliant

This list may not be complete