of the deeds of desperate valour there done , by the chieftains of the noble houses and their warriors , and not least by tuor , much is told in the fall of gondolin : of the battle of ecthelion of the fountain with gothmog lord of balrogs in the very square of the king , where each slew the other , and of the defence of the tower of turgon by the people of his household , until the tower was overthrown ; and mighty was its fall and the fall of turgon in its ruin .