Believe it or not, Ben Affleck was cast as the Dark Knight way back in August 2013. Cameras soon started rolling on Batman v Superman: Dawn of Justice, and the actor would go on to shoot a cameo role in Suicide Squad before returning for Justice League. With Joss Whedon at the helm of reshoots, the latter proved to be a disaster, though the other two movies were similarly negatively received.
As a result, it was no great surprise when Affleck decided not to star in and direct The Batman. Matt Reeves is now at the helm of that movie, though Robert Pattinson will be his Caped Crusader.
Affleck's attitude towards the role appears to have changed recently, though, as he returned to take part in Zack Snyder's Justice League reshoots and will be part of The Flash next year as well.
Yesterday was the actor's 49th birthday, and Snyder decided to celebrate by sharing a never-before-seen photo of Affleck decked out in the Batsuit for what we're assuming was the first time in 2013. The costume didn't go through a lot of changes after this, so we're guessing the filmmaker knew fairly early on what he wanted from his Bruce Wayne (a look inspired by Frank Miller's The Dark Knight Returns).
Check out Snyder's photo of the DCEU's original Batman below: