[6] During the following month Saracen conducted training exercises, then departed harbour for her first war patrol, off Norway, on 29 July 1942.

[6] On 31 August, Saracen was ordered to conduct a special patrol off Cape Finisterre, Spain, to intercept a possible German blockade runner.

After exercises off Gibraltar, Saracen conducted a patrol in the Alboran Sea from 17 to 27 September but sighted no potential targets.

One hour and a half later, Saracen surfaced again to signal the presence of the enemy submarine and was spotted by U-605 which had remained in the area.

The torpedoes were not noticed on board the British submarine, which then received orders to leave the area to allow surface ships to hunt U-605.

On her way to the patrol area, the submarine was attacked by German Messerschmitt Bf 109 fighter-bombers, sustaining slight damage to her wireless transmitter.

[9][12] One week later, Saracen launched three torpedoes at the German merchant ship Menes in the Gulf of Tunis, but missed, and the boat returned to Malta on 24 November.

On 22 December, Saracen twice sighted the Italian submarine Argento, but failed to manoeuvre into a suitable attack position.

[6] On 10 January 1943, Saracen departed Algiers for her seventh war patrol, close to Naples, in the Tyrrhenian Sea.

About 30 nautical miles (56 km; 35 mi) south of the island of Capri, the submarine sank the Italian patrol boat Maria Angeletta with gunfire on 20 January.

[13] On 22 and 23 January, Saracen missed a small oil tanker and an unidentified ship with four torpedoes each, then returned to Algiers on the 27th.

The next day, she sank with gunfire the Vichy French tugboats Provinçale II and Marseillaise V off Cape Sardineaux, southern France.

On 19 February, Saracen surfaced and fired her deck gun into a small shipbuilding yard at Cervo, Italy.

Two days later, she sighted two German landing craft, but did not attack them due to their shallow draft, which would have caused torpedoes to run under.

[14] Francesco Crispi was transporting 1,085 soldiers to Bastia, and Saracen was attacked with depth charges by the escorting ships, but was not damaged.

The submarine then torpedoed and sank the Italian merchantman Tagliamento three days later, 35 nautical miles (65 km; 40 mi) south of the island of Pianosa, Italy; according to Saracen's logbook, "A sheet of orange flame went up hundreds of feet into the air and burning debris hurtled in all directions.

[6] On 27 June, the submarine departed Algiers to patrol east of Corsica and provide cover for the Allied landings in Sicily.

[15] Four days later, the submarine was detected with Asdic by an Italian destroyer 15 nautical miles (28 km; 17 mi) east of Bastia, which dropped 27 depth charges, causing considerable damage aboard Saracen.

[18] During her service with the Royal Navy Saracen sank 7 ships for a total of 16,039 GRT as well as a German and an Italian U-boat.