By December nineteen forty four, most people on the Allied side thought the war in Europe would be over by spring, and a fair number thought by Christmas.
The line ran along the German border. And one stretch of it, about eighty miles of hilly forest in Belgium and Luxembourg, was held very thinly indeed, by four divisions where a dozen might have been wanted.
Two of those divisions had been badly mauled and were sent there to recover. Two had arrived from America within the previous fortnight and had not been in action at all. It was where you put people to rest, because nothing happened there.
It was the Ardennes. It is the same forest as episode three of this series, and everybody had had four and a half years to think about that, and it had happened anyway.
The German plan was enormously ambitious and, by the assessment of most of the generals asked to carry it out, unrealistic.
The idea was to punch through the weak sector, cross the river Meuse, and drive north-west to Antwerp. Antwerp was the port that had finally solved the Allied supply problem, and taking it would cut the British and Canadian armies in the north off from the Americans in the south.
Twenty divisions were assembled for it, in secret, which by that stage of the war was an extraordinary achievement in itself.
The secrecy was maintained by methods that show what had been learned. Movement was at night only. Radio traffic about the operation was banned entirely, so that there was nothing for Bletchley to read, and orders went by telephone and by hand. Aircraft flew low along the front to mask the noise of tanks moving up.
And the attack was timed for a period of forecast bad weather, so that the overwhelming Allied advantage in aircraft would be grounded.
It began before dawn on the sixteenth of December, in thick fog and freezing rain, and it achieved complete surprise.
Allied intelligence had noticed some of the signs. Reports came in of increased rail movement, of new units identified, of prisoners talking about a coming offensive. The reports were assessed at higher headquarters and interpreted as defensive preparation, because the alternative reading was that Germany was about to launch a major offensive, and Germany was widely assessed as no longer capable of one.
Which is the same failure as episode three, in the same forest, from the same direction, made by different people for very similar reasons.
There was one more trick in it. A German commando unit under Otto Skorzeny put a few hundred English-speaking soldiers into captured American uniforms and jeeps and sent them through the lines to switch signposts, cut telephone wires and misdirect traffic. Very few of them achieved anything. The rumour of them achieved a great deal, and for a fortnight American sentries were stopping generals and demanding to know the capital of their home state or the name of a film star.
The line broke in several places. An entire regiment of one green American division was surrounded and surrendered, which was the largest mass surrender of American troops in the European war. The bulge that the attack pushed into the Allied line is what gave the battle its name.
A forest is not good tank country and the Ardennes has very few roads, which meant that the whole offensive depended on a handful of towns where roads met.
The most important was Bastogne, where seven roads converge.
The American command reacted faster than the German plan allowed for. The 101st Airborne Division, which was resting in France after Normandy and Holland and was short of winter clothing, ammunition and about a third of its men, was put on lorries and driven through the night to Bastogne, arriving hours before the Germans.
They were surrounded within days.
On the twenty-second of December, a German party came forward under a white flag with a written demand for surrender, pointing out, entirely accurately, that the town was encircled and that the alternative was annihilation.
The acting commander, Brigadier General Anthony McAuliffe, read it, and his recorded first reaction was a dismissive remark. His staff thought that this was as good a reply as any, and it was typed up formally and sent back. The reply, in full, was one word: Nuts.
The German officer receiving it asked what it meant. The American colonel handing it over told him it meant the same as go to hell.
Two things then decided the battle, and neither was heroic in the cinematic sense.
The first was fuel. The German plan depended on capturing Allied fuel dumps along the way, because there was not enough petrol to reach Antwerp otherwise. Several of the largest dumps were denied to them, in one case by American troops setting fire to a valley of stacked fuel cans and burning a hundred and twenty thousand gallons rather than let it be taken. Armoured columns ran dry and were abandoned by their crews.
The second was the sky. On the twenty-third of December, the weather cleared.
Thousands of Allied aircraft got up, and what had been an offensive moving under a lid of cloud became a column of vehicles on narrow forest roads with nowhere to hide. Supplies were parachuted into Bastogne the same day.
Patton's Third Army, meanwhile, had done something that is genuinely remarkable as a piece of staff work. Told on the nineteenth of December to disengage from an offensive facing east and attack north instead, they turned an entire army through ninety degrees, in winter, on icy roads, and had divisions attacking north within three days. The relief column reached Bastogne on the twenty-sixth.
The bulge was pushed back over the following month, and by the end of January the line was more or less where it had been in early December.
It was the largest and costliest battle the American army fought in the war. Around seventy-five thousand American casualties. German losses were of a similar order and were far less replaceable, and the armoured reserve that had been assembled for this attack was gone.
The weather was its own enemy. It was one of the coldest winters in decades, and troops on both sides fought in temperatures well below freezing, often without winter clothing, in snow, in forest. Frostbite casualties ran into the tens of thousands.
There were also atrocities. Near the village of Malmedy, a group of American prisoners was shot by an SS unit, and word of it spread along the front within a day and hardened the fighting considerably.
For the civilians of the Ardennes it was the second occupation in five years, and the towns that had been liberated in September were fought over again house by house. Several were destroyed more completely in December than they had been in nineteen forty.
The strategic effect was the opposite of what had been intended. Germany had spent its last mobile reserve, in the west, in a month, and when the Soviet winter offensive opened in the east in January, there was nothing left to move.
The word Nuts needs a footnote for anybody outside America in the nineteen forties. It was mild slang for nonsense or rubbish, closer to what an English general might have meant by rot. It became famous partly because it was so completely untranslatable.
McAuliffe was not the divisional commander. He was the artillery commander, in temporary charge because the actual commander was away at a conference in America, which is a good reminder of how much of history is decided by who happened to be in the room.
The intelligence failure has been studied for eighty years, and the conclusion is uncomfortable. The information was there. It was collected, filed and read. What was missing was anybody willing to believe a conclusion that contradicted what everybody knew to be true, which is the same sentence this series has now written three times.
Here is something to think about tonight. The same forest, the same direction, the same kind of failure, four and a half years apart. What would it actually take for an organisation to learn a lesson properly, rather than just remembering that something once happened?