John Grogan was appointed as a Temporary Sub Lieutenant in the South African Naval Force (Volunteer) on 30 April 1942 and was seconded to the Royal Navy. He volunteered for ‘Special Service’ and trained as a Charioteer.

As the No. 1 Crewman, he died from oxygen poisoning in a training accident on 8 November 1942. He and his No. 2 Crewman, Able Seaman Harold Victor ‘Geordie’ Worthy, were carrying out a training night Chariot attack on the battleship HMS HOWE which was moored in Loch Cairnbawn. They were forced to go deep during their run into the target. Whilst underneath the battleship Grogan became unconscious. Being dived underneath the target they were unable to surface immediately. Worthy was forced to hold on to Grogan and also to control the Chariot at the same time as getting back to the surface and clear of the battleship, but it was too late to save Sub Lieutenant Grogan.

John Grogan was the son of Meredyth Grogan and Gabrielle M A Grogan. He is commemorated on the Plymouth Naval Memorial on Panel No. 74 Column No. 1, on the Simonstown Naval Memorial, Cape Town, South Africa, on the 12th Submarine Flotilla Memorial at Rothesay on the Isle of Bute and, on the 12th Submarine Flotilla Memorial Cairn, Garbh Eilan, Kylesku, Scotland.