May ninth was a disastrous date in The Power of Five, marking the beginning of the war which started in Hong Kong. It was the destruction of London and many other cities in the United Kingdom. Susan Ashwood said it was biological-nuclear bombs being fired on different cities, leaving them in ruins.
The effects were so that corpses were left rotting where they stood.
The survivors were few, but the ones who managed became zombie-like creatures in a derelict wasteland and mutated due to the radiation. Ashwood also said that there was some virus, it is unknown if this produced the mutations.
Sick dogs also roamed everywhere; eating each other if injured. Other survivors degenerated into cannibals. The giant spider was positioned in the ruins of London to hunt down Matt.
St Merediths church was left standing on purpose to capture Gatekeepers.
Most of London was destroyed; the Underground was just heavily polluted. Susan and some other non-mutated survivors took refuge in an underground pod used for this purpose. They still had electricity.
The United Kingdom was left a toxic wasteland due to all the explosions. Only two known villages - Holly's village and the Little Moulsford survived rather intact.