WATCH: How were trees used to kill and spy in WWI?

In the beginnings of World War I, the French military was looking for an effective way to hide its soldiers and arms from German fire.

The French eventually resorted to camouflage to trick the German forces on the battle fronts.

General de Castelnau told French painter Lucien-Victor Guirand de Scevola to develop ways to hide the soldiers, especially those who are assigned to monitoring front lines.

That is when they started using “fake trees”. The French built their iron monitoring towers and hid them by covering them with tree branches and leafs.

The first time the technique was used was in May 1915 during the Second Battle of Artois, when it was used to monitor German basis and directing artillery.

With the success of the idea, the British sent a number of experts to learn the technique from their French allies. The British officials further developed the technique to finally make trees that look exactly similar to the real trees.

The leadership of the British military assigned studying the French technique to the British painter Solomon Joseph Solomon, who made a research team of engineers to conduct research on one tree before presenting their findings.

Solomon used Leon Underwood, a British sculptor, to build a tree-like monitoring tower that was built from iron cylinders wide enough to cover a soldier.

Inside the cylinder, the painter put a 10 ft. ladder that has a chair on top, where the soldier can sit and monitor movements of the enemy.

The British army had to wait till night time to replace the real trees with fake ones.