Final answer:
The Halifax Harbour served as an important port and played a significant role during the First World War. It was a key supply base for naval operations and experienced the Halifax Explosion, which had both devastating and positive consequences for the war effort.
Step-by-step explanation:
The Halifax Harbour played a significant role during the First World War. One of its major contributions was serving as an important port for naval operations. It served as a key supply base for Canadian as well as Allied ships, allowing them to resupply and refuel on their way to Europe.
The harbour also played a role in the war through the Halifax Explosion in 1917, which was the largest man-made explosion before the atomic bomb. It resulted in significant damage and loss of life, but it also led to increased support and resources being directed towards the war effort.