"Bonfire of Dreams" is episode 22 of the Berserk manga.
Casca removes Guts' bandages and administers the elf dust. As she does, Guts explains that while fighting a hundred men as he did may be impressive, it's not as admirable as what Griffith or Casca do - fighting for a dream, for something noble. He tells her that within the Band of the Falcon's ranks, there are mercenaries who have their own hopes and dreams, and they all fight for it.
Guts likens their dreams to the bonfires set up around the camp; easily blown out by the wind, so they join a bigger, more resistant flame: Griffith's dream. Guts feels his fire isn't with the band. Casca suddenly realizes he means to leave it, but he assures her that he will stay with them until their campaign ends.
Their conversation is interrupted by Rickert and Pippin, who come to inform them that Griffith, upon hearing that they were safe, rushed back to the camp. Casca greets him first, apologizing for going into battle while she was unwell. Her apology is undermined by Guts, who slaps her on the behind for being too dramatic.
Guts leaves with his men for a drink, leaving Casca with Griffith. She watches as Guts leaves, wondering whether he really intends to leave the Band of the Falcon.
Later into the campaign, Doldrey, a strategic castle under Tudor control, is under siege by Midland's forces. The castle is said to be impregnable. One of Midland's generals is informed by a foot soldier that Midland is suffering heavy losses, and Tudor has sent their most powerful regiment of soldiers, the Holy Purple Rhino Knights, to attack Midland's battlefield headquarters.