Captain America #306

Direct

As Captain America and Captain Britain find themselves chained in a dungeon, Modred uses the Captain Britain costume to lay waste to London, demanding that Merlin appear to fight him. The Captains succeed in freeing themselves and Cap Britain convinces Modred to give him his costume back so he can summon Merlin. The magician refuses to materialize, however, and the Captains have to take down Modred on their own. Once Modred has fallen, Merlin arrives and takes him into an alternate dimension.