The article that Jeffro mentions at the outset does in fact suggest that there was a buildup to the War, that it did not just happen by surprise. I don't see how this can be interpreted as the Watchtower saying that the war just happened, with no run-up...
"By 1914, long-standing rivalries among European powers had stretched nerves taut and produced two opposing alliances"
"At the time, the area called the Balkans was a politically volatile region chafing under the sovereignty of the bigger powers, and it was rife with secret societies scheming for independence." - No mention of Balkan Wars, but it's not like the article passed the Balkans off as inconsequential.
" Furthermore, in the prewar years, “a great tidal wave of hypernationalism swept over Europe,” says the book Cooperation Under Anarchy. "
“Once the [Schlieffen] plan was set in motion, the system of military alliances almost assured a general European war,” says World Book Encyclopedia."