Fisher ordered Cradock not to engage without Canopus after Cradock had already reported rounding Cape Horn without her. Poor communications led Cradock to send Glasgow into Coronel to collect messages. Von Spee learned that the cruiser was present and sailed south with his entire force. Glasgow's speed made her a threat to his freedom of movement because she could shadow the squadron and report its position to other British ships.
Chapter · 2:39:18-2:41:48
Glasgow triggers the Coronel contact chain
Fisher's late order, Cradock's attempt to collect messages through Glasgow, and von Spee's decision to hunt the cruiser produced the immediate contact chain.