The exact details of wars differ, but war is, was, and most likely will be about power. They just cover it up a lot. (Not to mention wait for an event they can use to cover it up)

That Jeruzalem was a pilgrim's destination made it a very good excuse to kick the backsides of the people who were in control. It was still about power.

The thing about power is that it is addictive, and that is the true reason that power corrupts, as those who have power always seek for more.

As such, leaders make pretty stories about why they need to do something that will increase their power if it goes as desired.

Note, an effective way to increase power is to keep your populace happy, and if your populace wants the chance to go on a pilgrimage to Jeruzalem, providing them with that is a handy tool to keep them happy.