The Serbian terrorist group known as the Black Hand was determined to assassinate Franz Ferdinand, a move which he succeeded in his second attempt, on 28 June 1914. The assassination gave grounds for Austria-Hungary to act against Serbia and send a severe ultimatum.
Imperialism and colonialism
Were one of the triggers, since they had been developing for decades.
1901 - 1915, New technology
1941- Russian-German war
caused by the German demand to build a railway linking Berlin to Baghdad. Russia reacted, as the road would link Germany to the oil-rich Middle East with an attractive consumer market, as well as passing through regions where the Russians intended to increase their influence