Canadian soldiers played an instrumental role in the Battle of Passchendaele in Belgium 100 years ago and, this weekend, members of the Vancouver-based Seaforth Highlanders of Canada are commemorating the battle that helped secure an Allied victory during the First World War.

The Battle of Passchendaele was as brutal and bloody as more renowned clashes like the Battle of Vimy Ridge but is often lost in the shadow of other war moments.

More than 4,000 Canadians were killed and almost 12,000 wounded at Passchendaele.

Private Charles Durfee Harper

Private Charles Durfee Harper was wounded as he advanced towards Crest Farm and was buried alive by German shell-fire. He survived the battle but suffered severe and permanent shell-shock. (Seaforth Highlanders of Canada Museum )

Ryan Difine is a platoon commander with the Seaforth Highlanders, an infantry regiment established by a group of Vancouverites of Scottish descent in 1910.

They are a reserve unit, made up of volunteer soldiers, and were called up by the Canadian Expeditionary Force during the First World War.  

The 72nd regiment was front and centre at the key battle in Belgium, part of the Third Battle of Ypres.

"This was ground that, since the beginning of the war in 1914, had been fought over constantly, resembling almost more of a football game with the line moving back one way, then back the other way, then back the other way," Difine told CBC host of The Early Edition Rick Cluff.

Crest Farm

Taking Crest Farm was the Seaforth Highlanders' greatest victory in World War I. (Seaforth Highlanders of Canada Museum )

Vital ground, many casualties

It was extremely vital ground, Difine said, which is why the Allied forces had continued pushing back and forth for it throughout the First World War.

By the time the Battle of Passchendaele happened in 1917, the area had been fought over for three years.

Lance Corporal James Rae, Seaforth Highlanders

Lance Corporal James Rae, 72nd Battalion Seaforth Highlanders of Canada. (Seaforth Highlanders of Canada Museum )

Within days of going to battle, nearly half of Seaforth Highlanders battalion were killed or injured, Difine said.

An estimated 500 or 600 soldiers from the battalion went in to take the Crest Farm hill on Oct, 30, 1917 and days later, by the time they were relieved on Nov. 2, they had suffered 274 casualties.

12th Brigade headquarters

The 12th Brigade headquarters at Kink Corner, Passchendaele. (Seaforth Highlanders of Canada Museum )

Reconnaissance efforts

Difine said, for him, the most important part of the battle was the reconnaissance efforts.

The day before the battle was planned, the commander of the battalion heard there was flooding on the field and decided to gather all the soldiers to find out more.

"It's a good thing they did, because when they showed up there, they noticed that a lake had formed in front of the hill," Difine said. "They spent a considerable amount of time there, on their bellies, essentially in no man's land, trying to figure out how to crack this nut."

Battle of Passchendaele

A German pill box bunker defending Passchendaele. (Seaforth Highlanders of Canada Museum )

Hours before the battle, they found a way through and were able to successfully change plans in time.

"We have a saying that time spent on reconnaissance is rarely wasted," he said. "That really just hammers home the importance of that and the importance of changing your mind, the importance of reacting to a changing situation."

Taking Crest Farm was the Seaforth Highlanders' greatest victory in the First World War. 

To hear more about the battle, click on the audio link below:

With files from The Early Edition.