"As we have seen, historians in hindsight do not know what exactly was going on, so how should "the people" have known, including soldiers?"
Propaganda during world war one was based on deliberately manipulating the realities of military life and distorting the reasons for going to war.
Below is an assortment of the "lies" Tommy Kenny told us as to why he and his mates enlisted to fight and die in World War One
Jim Carroll

Introduction
Upon Australia hearing the news of the declaration of war, the response was one of almost unanimous excitement and devotion. Not surprisingly, this initial eagerness resulted in Australia quickly fulfilling the quota of 20 000 men that she had pledged to the British Empire. Support, however, waned and measures had to be taken to ensure that the numbers the nation was offering could be met. Propaganda was used to influence people to think in a particular way. There were two types of war propaganda at the time. The first was recruitment propaganda, a popular method that influenced people to enlist. The second was conscription propaganda which encouraged people to vote for or against conscription.
The context of propaganda
From the beginning, Australians embraced World War I with an enthusiasm that had never been experienced before and will probably never be seen again. Australian men rushed to enlist in droves but many were turned away because they were not able to meet the rigorous physical standards of the time. These standards, which included a minimum height of at least 5ft 6in (167.6cm) and a chest size of 34in (86.4cm), as well as a full set of teeth without any fillings, may seem frivolous by today's standards but at the time for those who were unable to meet them the outcome was often devastating. Many men travelled hundreds of kilometres to attempt to enlist at a different office in the hope that perhaps a minor ailment, which was the reason for their previous rejection, could be overlooked.
While the initial response to war was one of extreme enthusiasm and patriotism towards Britain, support began to waver. It had reached a peak at the time of the landings at Gallipoli but it was not long after that the realisation of war hit Australian shores. With the first lists of casualties, the Australian public had a sudden and rude awakening that their fathers, brothers, sons, husbands and friends might not all return safely home as previously expected. The public's attitude turned quickly, which was reflected in weakened recruitment figures.
In response to Britain's request for more troops, the Commonwealth government realised that strategies had to be implemented to encourage more people to enlist. In July 1915 some standards for entry were amended to widen the target market for recruits. This included lowering the minimum height restriction to 5ft 2in (157.5cm), which enabled men who were not previously eligible to enlist, to do so. In that same July, a two-week recruitment campaign was run in Victoria to encourage more enlistments. As part of this drive, campaign meetings were held during which patriotic speeches were given, often by injured war heroes. In addition, films of heroic action on the battlefields of Gallipoli were shown. Among these various recruitment ploys, perhaps the most effective and popular types of propaganda were the colourful posters displayed everywhere across the nation.
Recruitment propaganda
Propaganda in World War I was particularly influential in the years 1915 and 1916 when it was at its peak, serving to recruit volunteers in the hundreds of thousands each year. The recruitment propaganda of the time achieved its aim in a number of ways. Firstly, it influenced men through means of persuasion, fear, guilt, confrontation and accusation. Secondly, it appealed to the emotions of the women, friends and family of those who were eligible to go to war but had not, to feel strongly enough to press them on the matter.
It was particularly the propaganda posters that were popular at the time. The reasons could be that they were cheap and easy to create, able to be displayed just about anywhere and, as with most visual forms, were immediately able to convey meaning to a wide audience. Their popularity and significance is confirmed even today by how frequently propaganda posters are referred to in books about the war.
Recruitment propaganda perhaps achieved success because it amplified the original reasons for Australians wanting to be involved in the war. It can be concluded that Australian propaganda posters utilised six different aspects to appeal to men to enlist. These included:
Appealing to their patriotism by summoning people to 'rally around the flag' and reminding them of their duty to the Empire and the British
Utilising a gender approach which made men feel they needed to enlist to prove their sporting aptitude, courage and masculinity.
Inviting peers and family to place pressure and shame on men for not applying in order to make them feel ashamed and cowardly.
Encouraging a spirit of adventure and a desire to see the world by using a recruitment poster which places emphasis on a physical, sport-like side of war.
Self-interest, including a chance to have a secure job which was relatively well paid.
Exaggerating the hatred and fear of the Germans by allowing people to think that they might attack their friends and families.
Recruitment propaganda, however, omitted important facts from the posters. These omissions gave people a false impression of what war was really like. The propaganda intentionally neglected to mention the realities which the soldiers had to endure, such as a rationed, unvaried diet, adverse climatic conditions, physically arduous training and, most importantly, the substantial risk of injury and death. See image 1
From image 1 we can see that this particular propaganda relies on persuasion to conform or 'join the crowd'. It gives the impression that their peers have joined and that they should do so, too, if they do not want to be left out. The poster tries to entice men to enlist by appealing to their competitive nature by making war seem like an adventurous sport. It does this by incorporating images of men with sporting equipment. As with all wartime propaganda, it does not acknowledge the harsh realties the men would face if they enlisted.
http://www.skwirk.com/p-c_s-14%20_u-42_t-47_c-139/propaganda/nsw/history/australia-and-world-war-i/recruitment-and-conscription

http://www.learnnc.org/lp/editions/ww1posters/contents

http://en.wikipedia.org/wiki/British_propaganda_during_World_War_I

http://www.authentichistory.com/1914-1920/2-homefront/1-propaganda/