'Tomorrow, When the War Began shows us that war always brings out the worst in people.'
War doesn't necessarily bring out the worst in people, but it can make it necessary to commit acts that would be considered taboo in an everyday situation.'Good' and 'Bad' are only relative terms and don't apply to the same degree in war. Because war can make it hard to accurately distinguish the difference between 'good' and 'bad', it can be easy to take advantage of the situation. When we don't have set guidelines that tell us what is 'good' and what is 'bad' (murder is bad, and sharing is good, etc.) that make up the foundation of our society, then we are forced to create our own guidelines. The biggest problem with this is that not everyone's improvised morals will be mutual.
When the group is faced with a crisis they are forced to either disband the morals and dogma that they have always been taught, or be killed. They do no buckle under the pressure of war, and instead, they begin to act in a rational way, realising that the normal values no longer apply. When Ellie blows up the tractor, this gives evidence that she has left behing her old dogma, and created her own set of morals, which are more suited to the situation that she is in. Even though she doesn't realise it instantly.
In many ways, forcing the characters to make these moral decisions for themselves gives them responsibility, and subsequently a chance to prove themselves and grow as people. This lets them explore areas of ethics that they probably would never have been given the chance to do otherwise. When Ellie backs the truck over several soldiers, and act that probably would have saved their lives, she has trouble comprehending the magnitude of what she had done. It becomes a subconcious question of whether the end justifies the means for Ellie. Later on, she is able to justify it to herself, which proves that she can distinguish between 'right' and 'wrong' in a situation where survival is everybody's biggest concern. Another example of character change is Homer, at the beginning of the story, he is portrayed to be egotistic and immature. When forced to put his guise to one side, he shows himself for who he really is. This is an example of how war can bring out the good in people. But once again, does the end justify the means?
Homer's plan to blow up the bridge could be seen as questionable by many. If they are to go by their new moral rules that they have adopted for themselves, then logically, they should go ahead with it. But seeing as it is not comepletely necessary for their survival, and the fact that it could potentially harm many, should they once again adopt a new set of improvised morals? The answer to this is 'yes'. The people who they could possibly kill are not their personal enemies, they are either ignorant patriots or have been forced into war. In a way, the people that they are fighting are like them in many ways. The 'survival at all costs' mentality should only be adopted when it is absolutely necessary. By blowing up the bridge, and destroying a major supply line for the enemy invaders, they are damaging the enemy as a whole, but would it really be worth killing many innocent people?
In conclusion, the novel is trying to communicate that we shouldn't just use the morals that we have always been taught in our decision making, but rather create our own, to suit the situation using common sense.