Man you'r all bombarding spoilers... like rasengan for example. Or was it mentioned in anime yet?

And for the topic. The 3rd was getting old so they had to choose a new Hokage. And The Fourth (i don't remember/know his name) was chosen because he was at that time the most powerful and most fitting for Hokage job. You can guess that the Third who loves Konoha above all else wouldn't choose someone who doesn't feel the same way.

... and one day The Kyubi apeared! All the shinobis were sent to battle the Kyubi to delay it and that it wouldn't destroy the whole Konoha before The 4th arrived.
Maybe he was just late (Kakashi style) or maybe... he was preparing the jutsu or something.