In 1941 Western Approached Command had formed 8 escort groups.
The 1st Escort Group consisted of six destroyers and four Flower-class corvettes.

They were soon in action with other groups between 19 July – 1 August 1941 with Convoy ON 69 defending 26 merchant ships from 8 U-boats and 2 Italian submarines.

 In February and March 1942 the original eight escort groups were reorganized into the Mid-Ocean Escort Force (MOEF).
Alisma was part of Escort Group B7, one of seven such British naval groups which served with the Mid-Ocean Escort Force (MOEF).
It provided convoy protection in the most dangerous midsection of the North Atlantic route.
B7's first convoys, in the spring of 1942, were uneventful, and as the pace of the Battle of the Atlantic hotted up in the summer and autumn, the group's charges were escorted without loss.
But in December, while escorting ON 153, the convoy came under attack, and three ships were sunk.
During this action, on 11 December, Firedrake was torpedoed by the U-boat U-211 and sank with the loss of 168 of her crew, including her current commander, and the group's Senior Officer – Escort (SOE), Commander Eric Tilden.
Initially 35 survived the torpedoing, but only 27 managed to get on board Sunflower, which was under the command of Lieut- Commander John Treasure Jones.

B7 was involved in the battles for convoys ONS 20 and ON 206, ON 207 and ON 208, during which period nine U-boats were destroyed.
In 1941 Western Approached Command had formed 8 escort groups. The 1st Escort Group consisted of six destroyers and four Flower-class corvettes.
They were soon in action with other groups between 19 July – 1 August 1941 with Convoy ON 69 defending 26 merchant ships from 8 U-boats and 2 Italian submarines.
 In February and March 1942 the original eight escort groups were reorganized into the Mid-Ocean Escort Force (MOEF). Alisma was part of Escort Group B7, one of seven such British naval groups which served with the Mid-Ocean Escort Force (MOEF). It provided convoy protection in the most dangerous midsection of the North Atlantic route. B7's first convoys, in the spring of 1942, were uneventful, and as the pace of the Battle of the Atlantic hotted up in the summer and autumn, the group's charges were escorted without loss. But in December, while escorting ON 153, the convoy came under attack, and three ships were sunk. During this action, on 11 December, Firedrake was torpedoed by the U-boat U-211 and sank with the loss of 168 of her crew, including her current commander, and the group's Senior Officer – Escort (SOE), Commander Eric Tilden. Initially 35 survived the torpedoing, but only 27 managed to get on board Sunflower, which was under the command of Lieut- Commander John Treasure Jones.
B7 was involved in the battles for convoys ONS 20 and ON 206, ON 207 and ON 208, during which period nine U-boats were destroyed.
HMS Alisma (K185)