The ford was situated at a point where the Tamesis narrowed to less than half its usual width. In the middle of the river was a small island with a handful of willows growing either side of the track. The end of their long branches dipped down into the current and provided a green glimmering shade. Centurion Macro looked longingly at the shade as he mopped the sweat from his brow with the back of his hairy forearm. In a fleeting moment of fancy Macro imagined himself resting on his back under the willow, boots off and feet trailing in the cool water of the Tamesis. It was tempting . . . too tempting. He frowned and strode across the tiny island towards the north bank of the river. There was a shallow stretch of shingle over which the current swept, its disturbed surface glittering in the sunlight.

As soon as the Third Century had reached the ford, Macro had waded across to test the depth. The water came up to his waist when he reached the deepest part between the small island and each bank. Although his footing was firm enough the current was strong and might easily sweep away anyone who was careless as they crossed. Macro posted one section on the far bank to keep watch for the enemy and immediately set about preparing his defences. It was, perhaps, a hundred paces to the far bank and the width of the ford was no more than ten paces. Either side of the shingle bar the depth increased quickly and the riverbed was soft and covered with long reeds that slowly waved like hair beneath the surface of the river.

Macro had ordered half of his century to seed the ford with small sharpened stakes, and the men had hacked lengths of wood from the trees growing on the river banks and were busy driving them into the shingle, struggling against the pull of the current as they thrust the stakes in, angled towards the enemy shore. If the Britons were forced to use this ford the stakes would not stop them crossing, but might at least injure a few and slow down the rest.

Macro’s next line of defence was the small island, on which twenty men toiled to construct a rough barricade at the water’s edge. A dense tangle of branches and gorse had been dragged across from the south bank and piled up across the track in a line that extended either side of the shallows. Stout timbers had been pounded into the earth to brace the tangle, and other branches had been trimmed and sharpened and thrust in amongst the gorse to deter any attackers. It wasn’t much to look at, Macro decided, but it was the best they could do with the time and materials available.