...She did not, she merely ferried some of the delegates there. A classic job for second-rate vessels: assorted cruisers tended to be utilized for their speed over the more important big battlewagons, and for their availability.
Of the now more than half a dozen Trek Enterprises out there, only the E-D was the "Federation Flagship". Archer's NX-01 probably was a formally important vessel as well, being explicitly top of the line, although we never heard anything like this uttered on screen. Nothing Kirk ever flew was considered flagship, or even particularly special in her time (although Kirk's reputation eventually reflected on them). So far, nothing Pike has done with Kirk's eventual ship has forced us to rethink this.
Nothing flagshiplike was associated with the E-B or the E-C or the E-E, either, although of course all were big and powerful and advanced vessels for their day that in theory might have enjoyed some sort of a leading status.
The ship from the 2009 movie in turn was "our newest flagship", leaving open who "us" is supposed to be, and whether there would be one flagship for "us" or perhaps thirteen. When Pike handed the ship over to Kirk, she ceased to be referred to as a flagship, and never did anything particularly commanding (nor had a flag officer aboard). Her replacement seemed to be more of the same, and her role might have been implied to be one of exploration, ill suited for a flagship.
Timo Saloniemi