Because it’s an important perk of history ty
The military plans laid before World War I presupposed a major war between the countries which were tied together with alliances. Because the Triple Entente had Britain, France and Russia as allies, Germany thought if a war began it would need to fight on two fronts -- west and east. So German Field Marshall Alfred von Schlieffen drew up war plans that said attack France first, quickly, and then hold that territory while deploying forces to contend with Russia in the east. So when Germany declared war on Russia in 1914, the first thing it did was to go and attack France. Thus the war spread and became instantly a more global conflict.
National leaders in politics and the military need to learn caution when dealing with alliances and when committing themselves to military action. Restrained, limited military actions are preferable to the all-out plunging into war that was seen in the outbreak of World War I. Diplomacy should be given its best chance to work before resorting to military options -- even if military options have been pre-planned.
The Ottoman Empire contributed indirectly to the start of World War I by Balkan calls for independence, which contributed to instability in the region.
