Caspian skewers the first hobgoblin the enter the room, killing him and then back flipping to put distance between himself and the others. The second hobgoblin in the line strikes out at Caspian with a slash from his sword, hoping to catch the rogue before he escapes. The second row pair of hobgoblins move up behind him, stepping over their fallen comrade, to attack Ehrick with his pair of scimitars and Bruti, with his fearsome appearance.
The first slash cuts Caspian, but it is a minor flesh wound. The second row hobgoblins fail to hit their marks, the swords missing.
By my read of the rules, Caspian provokes an Attack of Opportunity; Disengage is an action that replaces an Attack, unless done as a bonus action allowed by a class feature. The one he attacked wouldn't have been able to do an AoO due to Fancy Footwork, but the one next to him can.