After completing work-up trials, Bonaventure sailed to Loch Striven on the west bank of the Clyde to become the main training base and depot ship for the X craft midget submarines.

In December she was nominated for deployment as the depot ship for the 14th Submarine Flotilla in the south west Pacific.

[1] Bonaventure arrived at Brisbane on 27 April and received approval to move nearer to the operational area and to approach the local US Navy authorities.

She subsequently sailed to Townsville, Queensland in May, where a visit was made by a senior officer of the 14th Flotilla to the US Navy Base at Subic Bay.

The Americans remained skeptical and suggested that Bonaventure be converted to perform a wider support role.

Bonaventure was transferred to Hervey Bay, Queensland in June, and then to an area south of Townsville, to prepare for the cable cutting operations.

She carried out extensive training and experiments off the coast of Mon Repos using a disused telegraph cable between Australia and New Caledonia.

Operation Struggle aimed to place limpet mines on the Japanese cruisers Myōkō and Takao, based at Singapore with the 10th Fleet.

For Operation Sabre, HMS Spearhead towed XE4, which succeeded in cutting two cables and bringing sections back to Bonaventure.

Operation Foil was undertaken with HMS Maidstone, based at Subic Bay, as the depot ship.