Margaret Brooke's heroism in the frigid waters of the Gulf of St. Lawrence is the stuff movies are made of. In the early morning of Oct. 14, 1942, the 27-year-old Royal Canadian Navy officer was aboard the SS Caribou, a ferry travelling between Sydney, N.S., and Port aux Basques, Nfld., when the vessel was hit by a torpedo from the German submarine U-69 in the Cabot Strait off Newfoundland.

Hours before the sinking, Margaret and her friend and nursing colleague, Sub-Lieutenant Agnes Wilkie, had decided to look for the life jackets in the cabin and Margaret worked out how to put them on. Luckily, they had a flashlight nearby later on, when they needed it.

"When the torpedo struck I was thrown across the room right on top of Agnes. I knew what had happened but for a second couldn't do anything. She [SLt. Wilkie] jumped up and grabbed the flashlight and climbed up for our life belts," she wrote in a letter sent home to her brother, Hewie, just after the incident. Dr. Brooke died in Victoria on Jan. 9 at the age of 100.

Story continues below advertisement

The torpedo struck at 3:14 a.m. SLt. Brooke described her shipmates on deck as "one terrified mob." The two women, who had managed to retrieve their "burberrys," or naval coats, didn't know to jump clear of the sinking vessel.

"We were sucked under with her. How we got away from her, I don't know, but we clung together somehow all the time we were under and when we finally reached the surface, we managed to grab a piece of wreckage and cling to that," she wrote to her brother.

A few minutes later, an overturned lifeboat floated by and they joined others clinging to ropes. A soldier helped SLt. Brooke up and then they pulled SLt. Wilkie out of the water. Soon, the weather and the frigid water brought on hypothermia.

SLt. Wilkie lost consciousness and let go but SLt. Brooke hauled her back, holding onto a rope on the lifeboat with one hand and her colleague with the other.

"I did manage to hold her until daybreak but then a wave pulled her right away from me. She didn't suffer [because she was unconscious] but it was so terrible to see her go."

Only SLt. Brooke and two or three other survivors were still clinging to the lifeboat half an hour later when the minesweeper HMCS Grandmere picked them up. The naval ship had been escorting the ferry, but it left the survivors to chase the German submarine; 136 of the 237 passengers died, many of them civilians, including children.

SLt. Wilkie was the only nurse in all three services – navy, air force and army – killed by enemy action in the Second World War, according to Cynthia Toman, the author of An Officer and a Lady, Canadian Military Nursing and the Second World War. SLt. Wilkie, 42, was a native of Carman, Man. She had volunteered for service while working as a nurse at the Misericordia Hospital in Winnipeg. She and SLt. Brooke travelled together on the train from Winnipeg returning from leave and had become close friends.

Story continues below advertisement

German U-boats caused havoc in the Gulf of St. Lawrence and the St. Lawrence River. Here is the Naval Museum of Quebec's tally of the losses: "Five naval ships were torpedoed, four of them Canadian, the fifth a United States Navy tanker. … On the St. Lawrence River and Gulf, 21 merchant ships were torpedoed. Seventeen of them sank, while four remained afloat."

The Battle of the St. Lawrence claimed a total of 340 Allied lives, about half of them members of the Royal Canadian Navy and Merchant Marine. The sinking of the SS Caribou was the single greatest loss of life. Four months after that sinking, the U-boat responsible, U-69, was forced to the surface by depth charges and rammed and sunk by a British destroyer in the North Atlantic. All 43 German sailors aboard perished.

Last April, the Royal Canadian Navy announced it would be naming one of its six new Arctic patrol vessels the HMCS Margaret Brooke, in her honour.

"Lieutenant-Commander [her rank when she retired] Brooke was a true Canadian naval hero," said Vice-Admiral Mark Norman, commander of the Royal Canadian Navy. It was the first time a Canadian ship had been named for a woman and the first time for a living person. All six of the new vessels are to be named after Canadians who served in the navy.

Dr. Brooke said she was blindsided by the news, which she received on her 100th birthday in a phone call from then-minister of national defence, Jason Kenney, as well as a personal visit from a ranking naval officer in Victoria, where she lived. She always preferred to be called Miss Brooke or Dr. Brooke, and chastised Mr. Kenney in the phone call for calling her Ms. Brooke.

"I've been astounded," she told The Globe and Mail in a phone interview in April of last year. "The navy doesn't just go around naming its ships after people."

Story continues below advertisement

Margaret Brooke was born April 10, 1915, in Ardath, Sask., and grew up on a farm there. Her father, Herbert, ran the farm and her mother, Maude, was a school teacher. When she was 18, Margaret and her brother, Hewitt, both left the farm for Saskatoon to attend the University of Saskatchewan, where Margaret earned a bachelor's degree in household science; her brother a medical degree. She went to work as a dietitian at the Ottawa Civic Hospital.

When the war broke out, she enlisted in the navy, and since they did not have a category for dietitians, she was made a nursing sister, with the rank of sub-lieutenant, the entry-level naval officer rank. Her brother, Hewitt, enlisted as a doctor and served on the HMCS Skeena, ending the war as a lieutenant-commander.

After the attack, SLt. Brooke took a month's leave and then worked in naval hospitals in Newfoundland and elsewhere for the rest of the war. For her heroism, she was made a military Member of the Order of the British Empire, a rare honour. The citation reads: "For gallantry and courage. After the sinking of the Newfoundland Ferry S.S. Caribou, this Officer displayed great courage whilst in the water in attempting to save the life of another Nursing Sister."

"Aunt Margie didn't like to talk about the Caribou incident but she did after the navy named the ship after her," said her niece, also named Margaret Brooke. "She said that in some book they said [the survivors] were singing hymns. She told me, 'Don't let anyone tell you we were singing hymns.'"

After the war, she stayed in the navy, rising to the rank of lieutenant-commander, the equivalent of major, before retiring in 1962. She moved home to Saskatchewan, and enrolled at the University of Saskatchewan where she studied paleontology, eventually earning a PhD.

"Her thesis was on microfossils of the Jurassic system in Southern Saskatchewan," her professor and colleague, Glen Caldwell said. She stayed on at the University of Saskatchewan doing research in paleontology, which Dr. Caldwell described as the geological study of life on Earth. Many of the microfossils that fascinated her were tiny sea creatures that once lived in the sea that covered Southern Saskatchewan.

Story continues below advertisement

She retired from the university in 1986 and moved to Victoria, where she had once been stationed as a naval officer. She led an active life there, and among other things joined a volunteer group that tended the gardens at the Lieutenant-Governor's residence, a few blocks from her home.

One of the many things she was involved in was fact-checking for a Saskatoon writer, Suzanne North, who was working on a novel about farm life in pre-war Saskatchewan. When the novel, Flying Time, was published, Dr. Brooke was acknowledged in the foreword. The novel won an award and somehow came to the attention of André Kirouac, the director of the Naval Museum of Quebec City, which has a special section on the Battle of the St. Lawrence.

"As we were trying to find any details about Dr. Brooke's career, we suspected she could be still alive somewhere in Canada. The book was in fact a door opener on the path to find her niece and then Dr. Brooke herself," Mr. Kirouac said.

There followed a series of interviews in newspapers and on the CBC. Dr. Brooke was modest about her role in the war.

"I think, just like everybody else, when the [Second World War] came along, we were all anxious to help out in some way. So I applied to the navy, and next thing I knew, I was on my way to Newfoundland," she said in an interview last year.

Dr. Brooke lived on her own until she was 97, when she fractured her hip. She remained in good health until contracting pneumonia last fall. She leaves five nieces and nephews, six great-nieces and great-nephews and one great-great-nephew.