On the morning of December 6th, 1917, a French cargo ship the "SS Mont Blanc" -- carrying tons of munitions bound for the allies during World War I -- collided with the "SS Imo," a Belgium relief ship, and eventually erupted into a fiery explosion in the harbor of Halifax, Nova Scotia.
Nearly 2,000 people were killed, and 9,000 were injured.
Within hours, officials in Boston sent a relief train stuffed with food, water and medical supplies about 400 miles to their neighbor up north. A blizzard delayed the train which arrived December 8, 1917.
On December 3 of this year, almost 98 years later, a delegation from Nova Scotia were in Boston to attend its annual tree lighting ceremony and remember the Halifax explosion. At a reception at the Omni Parker Hotel, the Mayor of Halifax, Michael Savage, put the disaster into perspective.
"If you put that in the context of today's population of Halifax, it would mean about 10,000 people dying and about 50,000 injured from one explosion."
It was the largest pre-nuclear man-made explosion in history. Nearly all the structures within a half-mile radius were destroyed. Windows were reportedly blown out 50 miles away, and the shockwave felt as far away as 200 miles from Halifax. Thousands were left homeless just before Christmas.
Savage was joined on the trip by the Premier of Nova Scotia, Stephen McNeil.
During a Halifax flag raising ceremony outside Boston City Hall, McNeil said, "We're here to say thank you. During a dark day in our Province's history, you extended a helping hand."
In honor of the city that rushed to their side, the citizens of Nova Scotia have delivered a Christmas tree every year since the 70's. It's Tim Whynot's job to scour the Canadian countryside for the best Christmas tree for Boston.
"We're looking for something very tall, forty to fifty feet, preferably closer to fifty feet. Very symmetrical, just like a regular Christmas tree except a lot taller," said Whynot. "This is the highest profile project I'm involved with in Nova Scotia,"
This year's tree was a white spruce donated by the MacEachern family from Pictou County, which is in the northern part of Nova Scotia. Andrea MacEachern accompanied Savage and McNeil to Boston for the tree lighting ceremony.
"That tree sat right outside our bedroom window, so it was the first thing I saw in the morning the last thing I saw at night," said MacEachern. "I wanted to see it lit up the day that we moved into the house. I'm going to see it lit up."
It was MacEachern's first trip to Boston, and she arrived a few days early with her 26-year-old daughter, Kyla.
"I can't get over how the people here are so thankful. They keep coming up to us, and when they realize that we are the tree donors, they keep coming up to us and saying, 'Thank you,'" said MacEachern. "So, thank you, city of Boston, for welcoming us into your city and being part of such a wonderful historical event. "
The delegation from Nova Scotia received a Boston Police Department escort to the tree lighting ceremony. A symbol of unity during a time of relentless tragedy.
"When you look at the world and you think about San Bernardino, you think about Paris, you think about Beirut, you think about what happened in Mali... there are a lot of lessons to try and make something positive come out of tragedy, said Savage. "Certainly in Halifax and Nova Scotia, we want to do our part to make life a little bit better for those that are suffering."
The disaster may have destroyed Halifax 98 years ago. But the tragedy has forever united two cities with a lasting tradition.