The "shopping list" of the Kaiser's colonies and dependencies was drawn up before the war: German East Africa, Cameroon, Nigeria, German Samoa - they would be divvied up between Britain and its colonies.

So it was that on the morning of August 29, the troopships Monowai and Moeraki, escorted by six warships, rolled across the reef on a gentle Pacific swell and up to the Apia dock. There were 1400 soldiers on board but not a shot was fired that first day.

Regrettably, says respected historian Stevan Eldred-Grigg, it was the calm before a brutal storm.

The behaviour of New Zealand troops in World War I was often characterised by mass beatings, cold-blooded killings, drunken violence and the sexual abuse of women and children.

These, say Eldred-Grigg, were the tools of empire.

In a new history that is bound to provoke controversy and fury from some, he writes of Imperial New Zealand - an aggressive state that did not blunder or blindly follow the British mother country into the so-called "Great War", but instead deliberately planned its colonial carve-up even before the conflict began.

Eldred-Grigg's new book, The Great Wrong War, challenges existing perceptions of New Zealand's involvement in World War I. He argues we had a choice about whether to go to war and that we chose wrong.

Mere days after the occupation of German Samoa, 2000 Chinese indentured labourers walked off plantations on strike and gathered outside the court house in Apia. Accounts at the time spoke lightly, almost frivolously, of a "little demonstration with the bayonet".

The truth, says Eldred-Grigg, was far worse. The workers were beaten with batons, clubbed and stabbed with bayonets, then driven away.

Two days later it happened again, when a group of workers requested the New Zealand military release their imprisoned compatriots. One plantation worker was summarily shot. The written account of one shocked young Kiwi soldier tells how the workers were "knocked about cruelly".

"Many Samoans are still angry today," says Eldred-Grigg, adding that in Samoa many look back to the German administration as a holiday or with a sense of nostalgia.

New Zealand's military discipline was as bad, if not worse, in Egypt.

The Dominion's soldiers commandeered labour, cash, goods, and livestock. They rounded up young men at the point of bayonet to serve as unwilling auxiliaries for the war.

Letters from the men on the ground describe New Zealand troops as having a brutally overbearing attitude towards the locals. Soldiers would beat locals for any reason or no reason. One account told of a soldier shooting a vendor dead from the window of a railway carriage.

Soldiers would go into a bar where they would jump on the table and yell "rough house".

The troops would start smashing chairs and fight while others rolled kegs and anything else they wanted out the door without paying. The powerless owners gathered what they could and ran away.

Even worse, New Zealand soldiers exploited boys, girls and women in the sex industry. Thousands of sex slaves were kept under lock and key. Arab and African women prostitutes were sometimes licensed, sometimes not. Rent boys - mere children - were commonplace and unregulated.

A worried official from the Wellington Young Men's Christian Association visited the red light district, where he saw queues of 30 or 40 New Zealand soldiers lined up outside the brothels.

Dominion soldiers suppressed locals in Syria, Iraq and Palestine for the British, and stood by as phosphorus bombs were dropped on towns. They helped crush a mass movement for freedom and democracy - all in the name of fighting for those same freedoms.

The invasion of Gallipoli - often portrayed as the red-hot forge of New Zealand's national identity - was a breach of international law, writes Eldred-Grigg. But then, so too was our very declaration of war against Germany.

In the lead-up to war, New Zealand was wealthy and had one of the best education systems in the world. But its leaders wanted more.

They plotted Pacific domination. More than a decade before the war, the government talked of gathering Tonga, Samoa, Fiji and Hawaii into a "watery overseas empire".

The year before the war, New Zealand came to an understanding with Britain that if the King of Tonga, Auckland-educated George Tubou II, behaved in a way that could be "taken exception to", his country could be annexed by New Zealand.

Nauru was desired because its thick deposits of phosphate could be spread on New Zealand paddocks.

General Sir Alexander John Godley secretly planned for an offensive war and was backed by the the ruling party in government, the Reform Party.

He wrote that the best use of the Army after the outbreak of a war would be "an attack on German overseas territory", together with helping the British Empire keep its unlawful hold on occupied Egypt and (lastly) backing up the British Army in Europe.

After the war, Prime Minister William Massey left for the peace conference promising he would win back in German compensation every penny of the £100 million that New Zealand had spent on the war.

That, according to the Reserve Bank, is the equivalent of spending about $10 billion today.

In addition, exports were essentially halted to all but Allies during the war, costing the nation millions.

And, despite Prime Minister Massey's big promises, New Zealand received little to make amends. A few second-hand German ships, planes and pieces of industrial machinery; German Samoa, which cost more to run then it made, and a piece of Nauru which gave access to cheap phosphates for New Zealand farmers.

New Zealand was once considered the lucky land, rich and educated and full of promise.

But, says Eldred-Grigg, it chose a path of brutality.

He just hopes New Zealanders re-examine the reasons we have gone to war - "and not just World War I".

* The Great Wrong War, by Stevan Eldred-Grigg, Random House, RRP $55