Warmongering is the act of starting a war for no good or honourable reason. Two things can be taken into account when judging this:

1) What tactics were used to start the war? Many warmongers use underhanded and illegal tactics to give them an excuse to start a war. For example, the Nazi Party killed several prisoners and dressed them up as Polish soldiers to make it look like Poland was trying to invade Germany. Essentially, if a leader does something underhanded to give them a pretext to go to war, then this is definitely warmongering.

2) What was the reason for the war? In some cases, the fact that a leader started a war can be overlooked if it was done for a good reason, eg to defend your country against an invading force or to protect innocent people, as long as war was a reasonable response to the problem. These cases would not warrant a page, as they would have been done for a good reason. However, you must also take into account whether or not the war is a proportional response. For example, a leader declaring war because their country is invaded would not warrant a page, whereas doing so because another leader promoted policies the leader disagrees with would.