LONDON — It is one of the busiest airports in Europe. It survived World War II, when it served as a base for R.A.F. night fighters flying missions against Nazi Germany. It has just been brought to a standstill by the humble drone.

“This hasn’t happened anywhere in the world before,” said Richard Gill, the founder and chief executive of Drone Defence, which helps institutions guard their perimeters against drones.

The Gatwick shutdown scrambled hundreds of flights, stranded tens of thousands of passengers and reduced the British government to playing cat-and-mouse with the drones. Controlled, perhaps, by little more than an iPad, they were repeatedly sent over the runway of the country’s second-largest airport in what officials called a “deliberate act.”

On Thursday, about 20 police units searched the perimeter of the airfield for the drones’ operators. By nightfall, the government said it would deploy the military in a bid to reopen the airport, though it was not clear what its role would be.