The battle of Messines fought on 7 June 1917 was the first large-scale action involving Australian troops in Belgium and it also marked the entry of the 3rd Division into a major battle. Messines was an important success for the British Army leading up to the beginning of the Third Battle of Ypres several weeks later.
At 3.10 am on 7 June 1917 nineteen powerful mines exploded under the German trenches along the Wytschaete – Messines ridge. Heavily supported by great volumes of artillery fire the British troops, commanded by General Sir Herbert Plumer, surged forward to capture the enemy positions. The 3rd Australian Division under Major-General John Monash, entering battle for the first time, was anxious to prove itself worthy of the reputation of the other veteran Australian divisions. It made a very successful attack alongside the New Zealand Division just south of the Messines village. The other Australian division involved, the 4th, under Major-General William Holmes, made a follow-up attack later in the day. Although some fighting continued, the result was virtually decided by the end of the first evening with the ridge being taken and enemy counter-attacks repulsed.
Read more on Messines (48 pages) - The Official History
The Battle of Messines / Charles Wheeler (1923).