A U.S. Army Humvee laying a smoke screen

A smoke-screen is a release of smoke in order to mask the movement or location of military units such as infantry, tanks or ships.

It is most commonly deployed in a canister, usually as a grenade. The grenade releases a very dense cloud of smoke designed to fill the surrounding area even in light wind. They have also been used by ships.

Whereas smokecreens would originally have been used to hide movement from enemies' line of sight, modern technology means that they are now also available in new forms; they can screen in the infrared as well as visible spectrum of light to prevent detection by infrared sensors or viewers, and also available for vehicles is a superdense form used to prevent laser beams of enemy target designators or range finders on vehicles.

Technology

Smoke grenades

Smoke grenade

These are canister-type grenades used as a ground-to-ground or ground-to-air signaling device. The body consists of a sheet steel cylinder with a few emission holes on top and at the bottom to allow smoke release when the grenade is ignited. The filler consists of 250 to 350 grams of colored (red, green, yellow or violet) smoke mixture (mostly potassium chlorate, lactose and a dye). Another type of smoke grenades, are the bursting kind. These are filled with white phosphorus (WP), which are spread by explosive action. The phosphorus catches fire in the presence of air, and burns with a brilliant yellow flame, while producing copious amounts of white smoke (phosphorus pentoxide). These doubles as incendiary grenades

Tactics

Land fighting

Smoke-screens are usually used by infantry to cover movement in areas of exposure to enemy fire, they can also be used by armoured fighting vehicles, such as tanks, to cover a withdrawal.

Notable uses of smoke-screens in naval warfare

Smoke-screens were used during the Battle of Jutland in World War I.

In the Battle of the River Plate in World War II, the German pocket battleship Admiral Graf Spee used a smoke-screen to escape from the British cruisers.

In the Second Battle of the Atlantic in World War II, smoke screens were used by Allied destroyer escorts to mask the presence of the merchant ships from German U-boats.