Can't See the Tree for the Wood

When British forces captured the Oosttaverne Wood from the Germans during the Battle of Messines in June 1917, they were surprised to find that one of the trees wasn’t a tree at all—it was a steel-and-iron imitation. This camouflaged “tree” had been used by the Germans as an outlook post to spy on the British lines without being detected.

The German “tree” found in Oosttaverne Wood

The British and French also used metal “trees” for observation during World War I. The Germans called the “trees” Baumbeobachter, which literally means “tree observer.” Because the enemy frontlines were watched so closely, any obvious observation methods would be easily spotted. So both sides used Baumbeobachters since they could easily blend into their surroundings.

An Australian-built Baumbeobachter

The Baumbeobachters were hollow steel tubes covered by iron “bark” textured to look like the real thing. The base of the steel tree widened and was buried in the ground to provide support.

The base to a German camouflage tree. This would have been sunk into the ground to provide support for the tree and also to allow access unseen by the enemy.

Close up of the coating on the steel ‘bark’

The observer would access the top of the observation post by climbing inside through a small opening close to the ground then ascending a narrow ladder, not much wider than a man’s boot. The rungs of the ladder were not very far apart, as the small circumference of the interior would prevent anyone from taking large steps.

The entrance to a tree, showing initials carved in its interior by an observer, January 1918.

A section of the ladder from the tree, compared to the size of a man\'s foot.

Once the observer climbed the ladder, he would sit on a small seat attached to the side of the tube. The seat was lower than the sight holes so any bullets or shrapnel that made it in through those openings wouldn’t directly hit the person inside; instead the observer used a periscope to see out.

Section of steel tube with the small and uncomfortable steel seat.

When an army decided they needed a Baumbeobachter, they would find a real tree in a location where they wanted their observation post. They’d have to choose a place along their frontline that was fairly static to put their Baumbeobachter; otherwise, if the line moved, the post would be useless. Then they’d take a picture of the real tree, and the Baumbeobachter would be made to look exactly like the existing tree. Once the army had the fake tree, they would cut down the real tree at night (sometimes under the cover of artillery fire to hide the sound), then put the Baumbeobachter exactly where the old tree was. That way, when the opposing army looked over in the morning, nothing would rouse their suspicions since everything looked exactly the same.

Putting up a camouflage tree (artwork by GC Leon Underwood, 1919)

Source:   http://www.awm.gov.au/blog/2008/06/03/cant-see-the-tree-for-the-wood/