Abatis

Abatis, Abattis or Abbattis (a French word meaning a heap of material thrown), a term in field fortification for an obstacle formed of the branches of trees laid in a row, with the tops directed towards the enemy and interlaced or tied with wire. The abatis is used alone or in combination with wire entanglements and other obstacles.

From 1911 Encyclopaedia Britannica

Although used since at least Roman Imperial times, abatis is rarely seen nowdays, having been largely replaced by wire obstacles. However it may be used as a supplement when barbed wire is in short supply. Also, a form of giant abatis, using whole trees instead of branches, can be used as an anti-tank obstacle.

An important weakness of abatis - in comparison to barbed wire - is that if time allows, it can be destroyed by fire. Also if it is laced together with rope instead of wire, the rope can be very quickly destroyed by fire, after which the abatis can be quickly pulled apart by grappling hooks thrown from a safe distance.

See also:

• mediaeval fortification
• caltrop
• cheval de frise
• trou de loup