U-21 had penetrated the Firth of Forth approaches and was sighted closely enough for a coastal battery beneath the Forth Bridge to open fire. The shots failed, and the British response lacked the sensors, command arrangements, and dedicated forces needed for a submarine hunt. Requisitioned trawlers could have searched the area, but only a limited number had entered service by September 1914. Britain had suitable civilian vessels, but mobilization had not yet turned them into an operational anti-submarine force.
Notable Point · 24:02-24:45
A submarine sighting without a hunting force
A reported periscope and unsuccessful shore-battery fire exposed how few requisitioned trawlers and organized submarine-hunting tools Britain had ready in September 1914.