Traction-catapults were strange beasts in that they had most power at maximum range. They lobbed their missiles up in the sky. The higher they went, the harder they hit. The two teams of ex-slaves Shef had left behind with their cart and their machines had accordingly set up their pull-throwers a carefully paced two hundred yards behind Sigvarth’s breastwork on the causeway; their missiles would strike twenty-five yards further on.

The narrow causeway was the ideal killing-ground for the machines. They threw perfectly straight, never deviating more than a few feet either side of the center. The English freedmen had perfected a drill designed to ensure that everyone did everything exactly the same way every time, and as fast as possible. For three minutes they shot. Then stood easy, panting.

The boulders dropped death from the sky on the Mercian column. The first one struck a tall warrior on the head as he stood unmoving, beating his skull almost into his shoulders. The second hit an automatically raised shield, shattering the arm behind it, caroming off to smash in a rib cage. The third hit a turned back, crushing the spine. In instants the causeway was jammed with struggling men, attempting to get back and away from a death they still could not see or understand. On the packed mass the stones continued to fall, varying a few yards forward or back as the launchers’ heaves fluctuated, but never missing the causeway itself. Only those who crowded forward into the ditch closest to the Vikings remained safe.

At the end of the three minutes the warriors leading the attack saw only chaos and ruin behind them. Those who fled to the rear saw now that at a certain distance they were safe.

Cwichelm, in the fore, waved his broadsword, yelled out in rage to Sigvarth, “Come out! Come out from your ditch and fight like men. With swords, not stones.”

Sigvarth’s yellow teeth showed again in a grin. “Come and make me,” he called, in an approximation of English. “You so brave. How many of you you need?”

More hours gained, he thought. How long does it take an Englishman to learn sense?

Not quite long enough, he reflected as the short February day drew toward its end in rain and sleet. The ditch and the stone-throwers had shocked them. But very, very slowly, maybe not quite slowly enough, they had got over their shock and worked out what they should have done in the first place.