Graham told the story of his adventurous father to Charlotte Evans for
Look Up Your Genes on BBC Radio Wales.
On 6 December 1917, the steamship Imo was leaving the harbour at Halifax when it was in collision with the Mont Blanc, a French munitions vessel carrying thousands of tons of TNT and other explosives into port.
The resulting explosions and fire destroyed two square miles of the city, leaving around 2,000 people dead and thousands more injured. The blast also caused a tidal wave which swept up the cove and swamped a Native American settlement.
Graham says it was one of the biggest ever man-made explosions, surpassed only when the first atomic bombs were dropped in 1945.
The Halifax disaster formed just part of his father's many adventures across north America as detailed in the postcards he sent home to the family in Wales.
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