Laurent Koscileny says he had to leave Arsenal because he was unhappy.
The French defender forced his way out of North London, eventually sealing a switch to Bordeaux.
"Nobody expected it.
"And with my family, we needed to go back to France and have a new challenge."
He congratulated his successor as captain, Pierre-Emerick Aubameyang, and recognised that the club is going through a difficult time at the moment.
"I'm happy for Aubameyang, and for his role as captain," he added.
"I wish them all the best, even if they are in a difficult period. But this is where we see a team and a collective ready to fight together and bounce back."