You’re understanding is in part correct. The militaries of all the major combatants had been building up during the long peacetime of the “Gilded Age” and were itching to try out all their new toys. Then dominoes fell in successive war declarations based on two alliances, the German Empire (the Second Reich) and Austria-Hungary (the Ottomans came in late seeing an opportunity to regain territory from Russia) on one side, and the British, French, Russians, and Italians on the other. The result shaped the rest of the twentieth century, from America becoming a reluctant participant in a European war, a Soviet Russia (with Stalin at the helm for thirty years), to an obscure Austrian corporal becoming a war hero and later world monster number two.
Fascinating. Incredible how Russia and America, England and France ended up fighting the same enemies in two world wars, and became such bad enemies afterwards.