Complex sentence: British battlecruisers were particularly vulnerable to cordite magazine explosions caused by fires or explosive flash spreading to them and three others-- "Invincible", "Indefatigable" and "Queen Mary"--blew up in the same battle for exactly this reason.
Split into simpler sentences: British battlecruisers were particularly vulnerable to cordite magazine explosions caused by fires or explosive flash spreading to them. Three others-- "Invincible", "Indefatigable" and "Queen Mary"--blew up in the same battle for exactly this reason.