In September 1944 as the Allies pushed east, the US First Army Command decided to take the Hürtgenwald -- a small triangular forest, roughly the size of Disney World in Florida, straddling the Seigfried Line. US intelligence said that much of the forest was deserted, and that the few remaining German soldiers were raw recruits and the "home-guard" – men unfit for combat. The intelligence was wrong, and this turned into the longest battle ever fought by the US Army.

Hürtgenwald was a state tree farm, made up of tall firs, planted so close together than in many places they formed an impassable wall, branches hanging down meant that you could only see a few feet in any direction, and it was covered with ridges and deep gorges. People said it was like a green cave – dark, gloomy, "weird and wild". Maps were virtually useless, and it was almost impossible to manoeuvre or reconnoitre as units found the strange place disorientating and became disorganised almost as soon as they were inside the wood.

As the German Army retreated east in the summer of 1944, they refortified the bunkers and pill boxes on the West wall of the Seigfried line where it ran through the forest, zeroed their artillery and mortars on the clearings, firebreaks and narrow trails that provided a way through, and littered them with landmines and booby-trapped rolls of barbed wire.

Hürtgenwald soon became known as "The Death Factory". The Germans knew they had to defend it at any cost, or be pushed back beyond the Rhine to defeat. The Americans were determined to take it.

Over the next five months, nine U.S. divisions were put through a meat-grinder – they were chewed up and spit out trying to force their way through the Hürtgen, with casualties put at 24,000 dead and wounded and another 9,000 suffering from illness and infections such as trench foot.

The Germans put up barrages which exploded up in the treetops showering bursts of shrapnel and tree splinters down onto the troops below, or targeted a single foxhole with a rain of shellfire until they got a direct hit, then moved on to target another.

The American tanks and bazookas were nearly useless against the heavy armour of the German tanks, and there were severe shortages of food and ammunition as the battle dragged on through Europe's worst winter in 40 years. Meanwhile the corps commanders and staff officers never visited the front, and did their work from their inaccurate maps and over radios and telephones.  And, unlike the company and platoon leaders, who bore the brunt of the fighting, the staff officers took few casualties, so the same men stayed at the same job, doing it badly.

The Schwammenauel dam and the forest were finally captured on 10 February 1945, by the 78th Division -- but it was a pyrrhic victory, bought at huge cost, the Americans' biggest blunder of the War.