Rather than a chance for new players to try out the game this is aimed at lapsed subscribers. To be eligible for the event you'll need to have purchased and registered the game before, but currently have an inactive account.
Defenders of Eorzea
Defenders of Eorzeaadds a bunch of new content including new gear, new dungeons to explore and new quests. Plus , which brings nostalgic/frustrating memories of Final Fantasy VII flooding back.
If you're wondering what's been going on in Final Fantasy XIV since you've been away, here's a chance to check it out for free.