41 years ago - Rick Flagg is born.
24 years ago - 17-year-old Rick enlists in the military and qualifies for special forces training.
21 years ago - 20-year-old Rick begins working in combat zones worldwide.
16 years ago - 25-year-old Rick starts working as a covert operative.
14 years ago - 27-year-old Rick is recruited into Checkmate by it's new head Amanda Waller, quickly becoming her go-to operative.
There is actually more than one Rick Flagg in DC's continuity. The original Rick Flagg was part of the original Suicide Squad, a team that operated during World War II. The Suicide Squad as we know them is actually a return to that original idea, and it was lead by Rick Flagg Jr, the son of the original. While this new character was actually pretty cool, as he was a main character in a very well written book (thank you, John Ostrander), one of the coolest things he did was die. That's not meant to be a slight against the character; his death drastically heightened the stakes of the book and made it a must-read.
Of course, any ongoing series dwindles in quality over time, and around the time they started messing with bringing Rick back, it was time to stop reading. Still, If we're going to make a Suicide Squad you basically HAVE to include Rick Flagg, as he's a key ingredient that gives the team the bulk of it's flavor.