History is important. It is a template for imagining the future and for analysing the present. In an age of slogans and soundbites when abbreviation is preferred to complexity, tales of Jewish history are marginalised and Zionist ideology demonised. The past is a foreign land to the purveyors of fake news.

The historian and archivist, Martin Sugarman, has consistently challenged this adulation of ignorance. He has written about buried subjects such as Jews in Japanese prisoner-of-war camps and Jews in the Fire Service in World War II.

In his latest book, Jews in the Merchant Navy in the Second World War, he has illuminated a secret history. Unlike the three main services, no concise records were kept about the Merchant Navy. This book is above all an attempt to rectify this oversight and to reclaim recent British Jewish history.

The Merchant Navy symbolically kept the home fires burning and prevented Britain’s isolation — and its dire consequences — by braving Hitler’s navy to transport vital supplies and armaments.

Those who manned the ships were all volunteers. It is believed that up to 185,000 men and women served in the Merchant Navy during the Second World War. Almost a fifth lost their lives on the high seas while 24,000 have no known grave except the cold waters of the world’s oceans.

The first Merchant Navy casualties occurred within hours of war being declared on September 3 1939 when a German U-boat attacked the SS Athena. The civilians on board were machine-gunned in the water. It set the scene for the rest of the war.

The Merchant Navy was traditionally international with many of the men and women coming from different ethnic and national groups. Japanese seamen served alongside their British compatriots until Pearl Harbour brought Japan into the war. Many Europeans whose countries had been occupied by the Nazis served in the Merchant Navy as part of the fight to liberate their homeland.

Jews had more than enough reason to stand up to the Nazis. As British citizens, it was a matter of freedom. As British Jews, it was a matter of life and death.

They understood that if Operation Sea Lion had gone ahead in 1940 and Hitler’s invasion of the British Isles been successful, there is no doubt that the Nazis would have separated British Jews from their non-Jewish fellow citizens.

Many of these British Jews were born just after the end of the First World War when the sentiment was to build a land fit for heroes after the slaughter of trench warfare.

The interwar reality was somewhat different. British Jews were discriminated against and impoverished. Indeed many British Jews anglicised their names in an attempt to become invisible and avoid antisemitism.

Jack Blonder, a cook on the SS Cape Corso, changed his name from Cohen. His ship was part of the PQ15 convoy to Murmansk in the then Soviet Union. It was sunk by a Heinkel torpedo bomber in May 1942. Blonder/Cohen was killed along with many of his shipmates.

The three Isbitsky brothers — David, Eddie and Sidney — changed their surname to Isbey. All served in the Merchant Navy. They had grown up in London’s East End and were well aware of what they were fighting for, having stood at the barricades against Oswald Mosley and the British Union of Fascists at the Battle of Cable Street in 1936.

Like the second generation of other immigrant groups, many of these British Jews distanced themselves from the past. Yet it was not just Hitler that jogged their collective memory. When Jack Aptaker signed on for the Merchant Navy, he was asked which religion he belonged to. A surprised Aptaker replied “Jewish”. The official authoritatively told him that in the Navy there were only two religions — Church of England and Roman Catholic. He was later taunted by cries of “why don’t you go back to Palestine?” from some of his shipmates.

Aptaker saw the full horror of war during the conflict. In the Far East he bore witness to the sight of the newly liberated British prisoners of Singapore’s Changi prison. The food was rationed to one slice of bread by their liberators since it was unclear how these walking skeletons would cope with more.

Aptaker’s growing awareness of his Jewishness and his fear of a repetition of atrocities led him to volunteer to serve in the Palmach during Israel’s war of independence.

The barrier between life and death could be remarkably thin. Alec Pressman, who had rescued men from the shores of Dunkirk in 1940, saw many of the ships he served on go down — and he miraculously survived.

On one occasion, his family was erroneously informed that he had drowned and his wife therefore started to sit shiva for her husband. Pressman magically appeared to attend the ceremony in person.

Some Jews who served in the Merchant Navy were escapees from Nazism. Charles Schaja Stenham belonged to Zionist youth groups in Leipzig and Dresden and fled Germany in July 1936 for kibbutz Degania (Aleph) in Palestine. He served on the ship MV Verbania and visited Jewish internees in Mauritius — they were refugees from the Patria, disastrously blown up by the Haganah in Haifa harbour, after the British had refused to allow them into Palestine.

Prisoner 82512, his number tattooed on his arm, served as a doctor at Auschwitz where the Nazis needed his medical expertise. Before the war, he was Dr Karel Sperber from Czechoslovakia. Escaping the Nazis in 1939, he joined the Merchant Navy as the ship’s purser on the SS Automedon. It was sunk and Sperber eventually found himself in German internment camps where he operated under the most primitive of conditions. He was credited with saving the lives of thousands of British prisoners when a typhus epidemic broke out in Stalag XB in the summer of 1941.

He survived Auschwitz and was awarded the OBE in 1946 for his services as a PoW doctor.

Henry Sless was born in the Gorbals in Glasgow, the son of immigrants from Eastern Europe. A marine engineer by profession, he was awarded the Distinguished Service Cross for his bravery in bringing the badly damaged SS Ohio to port from Gibraltar while under constant attack from the Luftwaffe. He was made an MBE (military) for staying at his post aboard the tanker, MV San Cipriano, on the Murmansk run.

Also from the Gorbals, Barnet Hanniford was a gunner aboard a DEMS (defensively equipped merchant ship) and is believed to have been awarded the BEM (British Empire Medal) for courage. In May 1943, he was serving on the SS Kanbe, carrying copper from Alexandria to the UK, when a U-boat torpedoed the ship off Liberia. The vessel went down within a couple of minutes. Most of the crew including Hanniford were killed. He left behind two young daughters who were brought up by his parents

Merchant shipman Captain Moshe Abramski of Palestine received the MBE for his gallantry in unloading fuel and ammunition from his ship under fire from Stuka fighter planes while docked in Tobruk, in Libya.

Churchill wrote that “the only thing that really frightened me during the war was the U-boat peril”.

Many who waved their fist at Hitler paid with their lives— and their heroism was remembered privately only by family and friends.

Primo Levi reminded us that those today “who live secure in your warm house” have an obligation to recall what happened so long ago and to pass these stories on to those who come after us. This is why Mr Sugarman’s book, and works like it, are so important.

Jews in the Merchant Navy in the Second World War is published by Vallentine Mitchell. Spiro Ark will launch the book on Wednesday, March 21, at 8pm at Hampstead Garden Suburb Synagogue​

Colin Shindler is a historian. His book ‘The Hebrew Republic: Israel’s Return to History’ is published by Rowman and Littlefield