The massive battle of Messines started, literally with a bang, on June 7, 1917 in Belgium and involved many of Otago's servicemen.
At 3.10am, 19 mines exploded beneath the German trenches under Messines Ridge, killing or burying alive an estimated 10,000 defenders.
The tremors of these explosions were felt as far away as southern England.
Testament to the raw force of the shockwave, four German officers were later found dead slumped over their dinner table behind a concrete pillbox without a mark on them, dying in an instant as they played their last game of bridge.
Immediately, the dazed German defenders on the ridge were subjected to massive artillery barrages followed closely by meticulously-planned infantry assaults by several British divisions and 2 Anzac Corps, which included General Andrew Russell's New Zealand Division.
Both battalions of the Otago Infantry Regiment were at the front of the first waves to sweep over the pulverised German trenches.
By early morning the infantry had reached their objectives on the ridge - a simple line on the map called the "Black Line" - with minimal casualties and began to dig in to repel the German counterattack and inevitable artillery barrages.
For the first time during the entire war, the battle was well planned and rehearsed, and for once, everything went to plan.
However, the plan itself was not without serious flaws, especially in a battle described as an artillery duel with a few infantry added to clear up strong-points and mop up the trenches.
The robotic General Sir Alexander Godley, commanding 2 Anzac Corps, refused to countenance Gen Russell's wish to withdraw most of his assault troops from the captured ridge.
Gen Russell wanted to quickly reduce the garrison and beat off the German counterattack with machine-guns and box barrages.
He was denied his wish and the New Zealanders suffered accordingly from massive barrages of high-explosive shells.
By the time the NZ Division was relieved two days later, it had suffered 3700 casualties including more than 700 dead.
Perhaps the strangest part of the battle was the use of cavalry to move beyond the Black Line, and into the newly created No Man's Land towards the "Black Dotted Line" - another line drawn on a map by staff officers to indicate the day's final objective.
One of the units charged with this deadly task was the Anzac Mounted Regiment.
This formation consisted of two squadrons of the 4th Australian Light Horse, and one squadron of the Otago Mounted Rifles.
This regiment was not attached to a particular division but was kept as divisional cavalry to 2 Anzac Corps, thus becoming the playthings of Gen Godley, who still considered cavalry had a role in this type of industrial warfare.
The Anzac Mounted Regiment's task was to capture any guns from the retreating Germans, mop up enemy stragglers and then report back to corps headquarters on the condition of the wire entanglements and defences at the Black Dotted Line.
The regiment probed forward late in the afternoon and was immediately subjected to very accurate German shellfire.
The ground they were expected to cross was an obstacle course of barbed wire and deep shell-holes still harbouring pockets of poisonous gas.
By 6.20pm, three parties of the Otago Mounted Rifles, totalling nearly 80 horsemen, moved forward again on horseback and penetrated a distance of nearly 1km in front of the infantry positions before more barbed wire and shelling made their passage impossible.
They quickly dismounted and continued on foot while the horses were sent back across the same shell-torn ground.
The German artillery had a field day causing mayhem among the hapless animals and their handlers.
The Otago Mounted Rifles finally withdrew at nightfall at the cost of one dead and six wounded.
Six Australian Light Horsemen also died in this attack.
But the horses suffered as well to satisfy Gen Godley's cavalry fantasies.
The Otagos lost eight horses killed outright by shellfire and had more than 30 badly wounded.
Two Dunedin men were decorated for their bravery in this ill-conceived action.
Second Lieutenant Edwin Wells was awarded the Military Cross, and Trooper Evan Lewis the Military Medal.
It has been argued that Messines was the first victory of the war where everything went to plan.
Up until that point, the British Empire's only "plan that went to plan" was the evacuation of the Gallipoli Peninsula.
Capture of the Messines Ridge wrested from the Germans a vital artillery vantage point overlooking the Lys Valley and the Ypres Salient in the weeks before the start of the massive Third Battle of Ypres that included Passchendaele, perhaps slightly reducing the awfulness of that tragedy.
