WWI AND WWII what factors contributed to the outbreak of hostilities?

the tipping point for WWI was because of the ination of Archduke Franz Ferdinand of Austria. That pissed off a lot of people and one by one countries joined in the fight for their own reasons. at the end of WW1 the United Nations was formed and they told Germany that they couldn't build any sort of army without their permission. When Hitler rose to power he said "to hell with the treaty" and started building his own army without the consent of the United Nations. Eventually Hitler started attacking other countries to try to gain power, and thus began the war to stop Hitler.