'This is about symbolism and sacrifice'
It was the first time soldiers of the 36th Ulster and 16th Irish Divisions fought side-by-side in World War One.
The centenary of the Battle of Messines Ridge is being commemorated with special ceremonies in Belgium.
Prince William, Taoiseach Enda Kenny and Princess Astrid of Belgium are among those attending the centenary services.
Mervyn Jess reports from the ceremony.
Read more here