How did World War I become a "total war"?

The American-English Dictionary defines total war as "war that is unrestricted in terms of the weapons used, the territory or combatants involved, or the objectives pursued, especially one in which the laws of war are disregarded." By that definition, World War I was certainly a prime example of total war. For this was a war the likes of which had never been seen before, involving the governments, economies, and civilian populations of the respective combatants to an unprecedented extent.
Previously, wars had tended to be relatively small affairs with limited aims, fought purely between the relevant combatants' armies. In World War I, however, that changed completely. War was no longer just a matter for soldiers, but for civilians as well. Now whole nations became involved in the military struggle. Every single aspect of national life was geared towards winning the war.
In Britain, for example, the government became involved in the running of the economy to a hitherto unimaginable extent. The government set production targets for armaments and munitions, nationalized factories, and allocated manpower and resources.
In Germany, meanwhile, the conscription of labor became a major part of the war effort. Under the so-called Auxiliary Service Law of 1916, the German government was given sweeping powers to employ and relocate any number of adult male citizens to satisfy the growing demands of a wartime economy operating at near full capacity.
Total war overturned many of the old social and political certainties, not just in relation to the role of the state in economic management. In Britain, somewhere between 700,000 and 1 million women were employed in munitions factories, manufacturing much-needed weapons for the British armed forces. Previously, such work was regarded as unsuitable for women and was the sole preserve of men. But with men desperately needed at the front, the Ministry of Munitions drafted women workers to help fill the gap created by mass conscription.
During the War, Britain, Germany, and a number of other countries witnessed a vast expansion of the state's police power. The exigencies of war-time permitted governments to arrogate to themselves a vast panoply of new powers, from the censorship of newspapers to the imprisonment of civilians without trial. Governments also greatly expanded surveillance and counter-subversion networks, designed to root out those considered a clear and present danger to national security. The systematic curtailment of civil liberties during wartime became a widespread feature among European democracies and, also, the United States. The demands of total war could be used as a pretext for governments to suppress radical political groups and movements, who would normally be protected by the rule of law.