Fort Widley is one of the forts built on top of Portsdown Hill between 1860 and 1868 on the recommendation of the Royal Commission on the Defence of the United Kingdom. It was designed, along with the other Palmerston Forts atop Portsdown, to protect Portsmouth from attack from the rear. In September 2010 the fort was used to host a search and rescue exercise based around a simulated earthquake. Titled Exercise Orion, the event involved teams from seven countries dealing with 35 scenarios over 2 days.