After completing trials and working up for operational service, in May the destroyer was nominated for escort of military convoys during their passage to Freetown.

On 6 July, Blackmore joined WS 20 as ocean escort, with the battleship Malaya the destroyers Brilliant and Wivern during the convoy's passage to the Cape of Good Hope.

[2] In August Blackmore joined the 57th Fleet Division based at Malta, and deployed for convoy defence in the central Mediterranean.

In September the destroyer joined a naval task force to escort and support the Allied invasion of Italy.

On 8 September the destroyer was deployed as an escort of the military convoy TSF1X during passage from Palermo to the Salerno beach head.

Between November and December, Blackmore joined the 60th Destroyer Division, also based in Malta but deploying for convoy defence and support duties of military operations in the Adriatic sea.

In July the destroyer continued in her deployment with the flotilla, this time with the nomination for escort and patrol duties of military convoys during Allied landings in the south of France.

In September Blackmore was recalled to the United Kingdom for a refit at Sheerness, before being nominated for service with the Eastern Fleet.

In March, Blackmore was deployed briefly for convoy defence, since additional escorts were needed to combat a concerted submarine and E-Boat attack in the Thames estuary.

Blackmore continued to be deployed in this theatre until August, sailing from Trincomalee on 4 September as part of the escort task force for aircraft carriers during their passage to the Malacca Straits.

On 6 September the destroyer joined military convoy JE1F, in the Malacca Straits, forming part of the escort in Operation Zipper.