The unique Second War ‘Battle of the Atlantic’ D.S.M. and Bar, M.I.D. group of five awarded to Acting Petty Officer J. P. Coster, Royal Navy, for services as senior Asdic operator (H.S.D.) aboard the destroyer H.M.S. Hesperus under Commander Donald Macintyre, D.S.O.**, D.S.C., one of the most successful wartime C.O.’s of convoy escorts in the Battle of the Atlantic and author of ‘U-Boat Killer’ amongst many others

Distinguished Service Medal, G.VI.R. (JX.148640 J. P. Coster. A/L. Smn.) impressed naming, with Second Award Bar, the reverse privately dated ‘1943’; 1939-45 Star; Atlantic Star, 1 clasp, France and Germany; Pacific Star; War Medal 1939-45, with M.I.D. oak leaf, the last four all privately impressed ‘JX.148640 J. P. Coster. D.S.M. & Bar. A/L. Smn. R.N. “H.M.S. Hesperus”, mounted as worn, nearly extremely fine (5) £4,000-£5,000

D.S.M. London Gazette 9 March 1943: ‘For skill and determination in action against enemy submarines while serving in H.M. Ships Hesperus and Vanessa. - Temporary Acting Leading Seaman James Philip Coster.

Seedies Roll confirms award for the destruction of U-357 in the north-western approaches on 26 December 1942. Commander Macintyre was awarded a Bar to his earlier D.S.O. for this action. U-357 was forced to the surface by depth charges and then rammed and sunk by Hesperus.

D.S.M. Second Award Bar London Gazette 11 January 1944: ‘For courage and great skill in successful attacks on U-boats while serving in H.M.S. Hesperus. - Temporary Acting Petty Officer James Philip Coster, D.S.M. (Newbury, Berkshire).’

Two recommendations exist in Admiralty files for this award and it appears that the two were rolled up together into the Second Award Bar. The first, submitted on 20 May 1943, states:
‘Leading Seaman (Higher Submarine Detector - H.S.D.) James Philip Coster. D.S.M. awarded 9 March 1943.
On Friday, 23rd April, 1943, when H.M.S. Hesperus was escorting Convoy O.N.S. 4, an enemy submarine was sighted and seen tio dive. This U-boat was soon afterwards picked up on the Asdics and a hunt ensued, at the end of which a hit with the Hedgehog was obtained and the U-boat sunk. Leading Seaman Coster was the asdic operator and his accurate and skilful operation of the set enabled contact with the submarine to be held throughout the hunt and accurate attacks to [be] delivered which resulted in the destruction of the U-boat.’

The second recommendation was submitted just 3 days later, on 23 May 1943, and states:

‘A/Petty Officer (Ty) James Philip Coster. D.S.M. awarded 9 March 1943. Previously recommended on 30 December 1942 and 20 May 1943.
On the night of 11th/12th May, and again on 12th May, 1943 H.M.S. Hesperus detected and attacked U-boats. In the first case, the U-boat was depth-charged and forced to the surface after several attacks. It was then attacked by gunfire and left sinking. In the second case, the U-boat was detected by Asdics and, after three depth-charge attacks, was heard to explode, wreckage coming to the surface to confirm the sinking. Petty Officer Coster was the A/S operator throughout both these actions and his cool and skilful operation of the A/S set enabled the accurate attacks to be delivered which resulted in the destruction of the U-boats.’

Seedies Roll confirms award for successful attacks on U-boats in May 1943, with one sunk and two destroyed. U-186 was confirmed sunk north of the Azores by depth charges from Hesperus.

M.I.D. London Gazette 23 November 1943: ‘For gallant and distinguished services in successful attacks on U-boats while serving in H.M. Ships... Hesperus.’
Seedies Roll confirms award for the probable destruction of a U-boat in the western approaches on 4 April 1943.

James Philip Coster was a native of Newbury, Berkshire. He was the only recipient of the D.S.M. and Bar in Hesperus and the only crew member to receive three awards in this ship. Captain Donald Macintyre gives a succinct description of the asdic and depth charge attack procedure employed against U-boats in the early days of the battle of the Atlantic in his book, U-Boat Killer:

‘Once it was decided to attack, the procedure was to point one’s ship at the target and close it at a moderate speed. By the time the range was down to about 1,000 yards, sufficient data would have reached the plot to give a course and speed of the target. Course would then be altered so as to ‘collide’ with the submarine, and as the ship passed over it, or rather passed a little way ahead to allow for the time taken by depth-charges to sink, a pattern of depth charges would be fired. Those from the chutes in the stern would be dropped at evenly-spaced intervals in the wake, while the depth-charge throwers would send others out some fifty yards on either side. Thus the pattern properly laid would form a shape like an elongated diamond, somewhere inside of which, one hoped, would be the target. But to produce lethal damage the charges must explode near the U-boat in depth as well as in plan and as the depth of the submarine was largely a matter of guesswork the charges were fired at varying depths to increase the chance of success.
Such in brief outline was the asdic and the depth charge attack as we knew them in the early days of the Atlantic battle. Of course, there were very many refinements of method and calculation. The effect of wind and weather on one’s ship and consequently on the best direction from which to attack, the need to avoid presenting oneself as an easy target for a torpedo attack in retaliation, the ruses tried out to prevent the U-boat commander from knowing when one was making the final dash to drop depth charges - all were of vital importance to the U-boat hunter.
I was wonderfully lucky in the ‘Ping’ specialists who served with me in the two ships wgich I commanded for long periods of the war. In Walker the senior asdic rating, Backhouse, had the quiet confidence of the man who knows his job through and through. At the climax of a long night of confused fighting and mêlée, he was quite unperturbed and was able to classify the sounds in his headphones with the detachment acquired through long and wearisome practise. Later in Hesperus I had the incomparable Petty-Officer Coster, who could be relied on to hear the first faint echo from a submarine at the maximum range of the asdic. Teamed up with Bill Ridley, my First-Lieutenant and anti-submarine specialist officer, they were a deadly combination for any U-boat that came within Hesperus range.’

Sold with 6pp copied reports and recommendations.