It was at this point that Boerzes came to the conclusion that what he was looking at probably wasn't a festival at all, but something rather more sinister. He therefore crawled in closer still (according to the report; some commentators have found it hard to credit much of what follows), and actually climbed up the blind side of the nearest machine and looked inside for some clue as to its function and purpose.
He saw (if the report is to be believed) a mechanism by which the weight of a heavy lead block suspended from a rope wound around a spindle turned a driveshaft connected to a gear train, which in turn drove a headstock to which were fixed four curved and twisted blades. From the shape and profile of these blades, he deduced in a sudden flash of insight that they were designed to cut and scoop earth. Furthermore, the sear that released the weight, allowing it to descend and thereby drive the mechanism, was connected to an elaborate system of wires and levers leading to a pressure point on the front of the machine, just above the tow-hitch; the implication being that when the machine crashed into a solid obstacle, such as a bank of earth, the weight would be tripped and the blades would start to turn, without the need of a human operator.
At this point (so the report states) Boerzes found himself torn between his perceived duty and his personal desire to engage the enemy and single-handedly thwart what he recognised as an entirely viable plan to breach the bank of the flooded ditch and thereby drain it. Again, his true motivation can only be guessed at; the report records that he settled himself on the top of the machine, nocked an arrow on his bowstring and started shooting.
If this is indeed what happened, it's easy to imagine the bewilderment and panic it caused. It's entirely plausible that the drovers and sappers believed they were being attacked by a sortie in force from the embankment. Allied accounts of the incident confirm the Mezentine report's assertion that at least one of Boerzes' arrows hit an ox, which shied, broke its traces and plunged into the crowd of sappers and lantern-bearers. Many of them understandably sought the nearest cover, some of them crowding behind the worms; Boerzes asserted that, having by this time run out of arrows, he killed two of them with his sword before making his escape back to the Mezentine lines. In any event, the allies halted their operations, and Boerzes, having made a frantic report to the watch captain, urged him to start an artillery bombardment at once, to smash down the posts cemented in at the foot of the trench.
The watch captain pointed out that most of the artillery crews had been sent home, and the only men available were partially trained general infantry, incapable of working the engines, let alone aiming with sufficient precision to take out the posts. Instead, having sent a message to Chairman Psellus, he took the decision to launch a sortie with the forces at his command.
Psellus' reply, forbidding him to leave his position under any circumstances, came too late, and the sortie, no more than sixty men strong, scrambled down the embankment into the flooded ditch. Since none of them had been trained to swim in armour, it was inevitable that a number of them soon got into difficulties and were drowned; others were saved by their fellows or managed somehow to get across, but the commotion they made soon drew the attention of the allied sappers, who by now had realised that they were no longer under attack and were hurrying to get the operation back on schedule.
The surviving members of the sortie, meanwhile, had reached the trench; but they were leaderless, the captain having drowned in the flooded ditch, and most of them had only a very vague idea of what the purpose of the sortie was supposed to be. Instead of breaking down the posts or cutting the ropes, they advanced slowly and warily up the trench, apparently expecting to meet a raiding party of allied infantry.
Instead, they met the worms. General Daurenja, directing this stage of the operation in person, had given the order for the oxen to be led forward, pulling on the ropes fed through the pulleys at the far end of the trench and thereby drawing the worms on their wheeled carriages down the trench towards the already weakened wall of the flooded ditch. The sortie took them for some kind of siege tower and, displaying a remarkable degree of courage in the circumstances, charged them and clambered aboard. Instead of finding them full of armed men, however, they quickly realised they were unmanned, and moving at a slow but steady rate towards the ditch. The sortie's nerve finally broke; they jumped down behind the worms, still not having the wit to cut the ropes, and tried to climb out of the trench over the gabion wall. In the dark, however, they had no idea how tall it was; they appeared to have concluded that it was too high to scale without ladders, and dropped back into the trench; for some reason, it didn't seem to have occurred to them to try the other side, where there was no wall and they could have scrambled out relatively easily. As a result, they were still in the trench when the worms hit the bank and set off their blade-spinning mechanisms.
Ziani Vaatzes had of course tested a prototype before shipping the worms to the camp; it helped, as well, that the weight of the ditch-water was pressing in from the other side. Even so, the speed and efficiency with which they bored through the bank surprised everybody, including the general. The bank collapsed and the water flooded out into the trench, sweeping before it a tumbled mess of gabions, shield trolleys, fascines and other equipment. Most probably it was the debris, rather than the floodwater, that accounted for the Mezentines in the trench; only six of them escaped to report back to Psellus on the embankment. The worms, on the other hand, remained firmly tethered to the posts, cemented into the trench floor, and when the water had drained away and the first allied troops arrived at the foot of the trench, they found them substantially intact, ready for use in the next stage of the operation. Psellus' head was still full of sleep as they bundled him, in his frayed nightgown and slippers, into the Guildhall yard, where a covered sedan chair was waiting. He protested: he hated being carried around in those things, he'd far rather walk. They ignored him as though he hadn't spoken, which put him in his place.
He particularly hated it when one of the four chairmen was a few inches taller than the others. It meant that one corner of the chair was always higher, while the man diagonally opposite was taking more than his fair share of the weight, which meant he stumbled on cobbles.
As a result, Psellus found it impossible to concentrate on what he'd been told, as the chair lurched and wobbled through the back alleys, heading for the Ridgeway gate. That was unfortunate; he needed time to clear his mind, before people started talking at him in loud voices. All he'd managed to grasp while they were waking him up and putting his slippers on his feet was that the enemy had somehow managed to burst the banks of the flooded ditch; there was also some ridiculous talk about a sortie-he'd sent a runner ahead to forestall that-and other stuff about monstrous unmanned digging machines. He'd let it flow over him; he'd have to deal with it when he got there, and the world stopped swaying.