Square Enix has released an official synopsis of the "End of an Era" trailer. This should help those of us who haven't been in-game for a longer period of time, to understand exactly why Dalamud fell, and Bahamut was released.
(Source)
Quote
<div class="blockquote"><div class='quote'>Eorzea. A Land embraced by Gods and forged by Heroes.
Seeking control over this realm and its abundant crystal resources, the Garlean Empire (a scientifically advanced nation hailing from the north) begins gathering an army of epic proportions. To ready themselves for the coming conflict, the city-states of Eorzea reinstate the Grand Companies
More...
(Source)
Quote
<div class="blockquote"><div class='quote'>Eorzea. A Land embraced by Gods and forged by Heroes.
Seeking control over this realm and its abundant crystal resources, the Garlean Empire (a scientifically advanced nation hailing from the north) begins gathering an army of epic proportions. To ready themselves for the coming conflict, the city-states of Eorzea reinstate the Grand Companies
More...