[1] He entered the Royal Australian Naval College, Jervis Bay at the age of 14, graduated three years later, and was promoted to midshipman in 1920.

In the first half of the 20th century, the RAN worked very closely with the British Royal Navy (RN), frequently exchanging personnel.

At the outbreak of World War II, Dechaineux was attached to the RN Tactical and Minesweeping divisions until April 1940.

At first, deployed from Dover, on 27 May the ship patrolled the beaches off Dunkirk, providing general anti-aircraft cover and protecting against fast E-boat attacks while scores of vessels crossed the mercifully semi-calm Channel in evacuation.

But her machineguns were no match for the attacking aircraft and occasional ship of the enemy: she was bombed as she reached the open sea outside Britain, and 40 on board were killed.

On 3 June the destroyer was directed to take part in Operation OK, which sank blockships, to provide a temporary wharfage point, in Dunkirk Harbour.

After working up to satisfactory operational capability in Scapa Flow – where the ship and her captain were assessed by RN experts – the last months of the year were spent on North Sea convoy escort duties, as was 1941, although on 4 October the ship carried out a brief search for a German destroyer reported minelaying off South Foreland.

In June 1943, following the outbreak of war with Japan, he was given command of the tactical (destroyer) component of RAN-US Navy Task Force 74.

Although the 200 kg (440 pound) bomb carried by the plane failed to explode, burning fuel and debris were spewed over a large area.