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MESSINES RIDGE, Belgium (Reuters) - Britain’s Prince William joined leaders and troops from Ireland, New Zealand and Australia in Belgium to honor those killed in the World War One Battle of Messines Ridge, launched 100 years ago on Wednesday.

“We will remember them,” intoned a crowd of several hundred during a ceremony at the Island of Ireland Peace Park, where Queen Elizabeth’s grandson, Irish Prime Minister Enda Kenny and Belgium’s Princess Astrid laid wreaths.

They were watched by descendants of some of the tens of thousands of men who fought in the week-long battle against German troops dug in on high ground near Ypres.

The battle is significant for Ireland as it saw the mainly Catholic 16th (Irish) Division and the 36th (Ulster) Division, raised in the mainly Protestant north of the island, fight alongside each other, just a year after the failed Easter Rising in Dublin against British rule.

Irish officials said Wednesday’s ceremonies were a chance to “reflect on the journey of reconciliation in the century since and to highlight the positive relationship that exists on the island of Ireland and between Ireland and the United Kingdom”.

Messines Ridge, generally seen as a victory for British-led forces and a prelude to the bigger Battle of Passchendaele in the same area through the summer and autumn of 1917, is also a focus of World War One remembrance in Australia and New Zealand.

Maori troops of the New Zealand Defence Force performed a traditional song at the start of early morning commemorations at another cemetery attended by Governor-General Patsy Reddy. Australia also held a centenary service on the battlefield.