Through the marsh which was left when the water disappeared the Romans constructed a navigable canal, now called the Fossdyke, between the Witham and the Trent. Its original course at the western end was, according to Stukeley, more direct than at present—joining the Trent not, as now, at Torksey, but about two miles farther south. From its bed was dredged up in 1774 a small bronze statue of Mars, with a Latin inscription. At Lincoln itself the Sincil Dyke, a drain of the “Slaker” type—to ease off the water in time of flood—was constructed connecting the upper and lower ends of the loop which is made by the Witham in order to pass through the Gap. These operations certainly took place at a very early period of the Roman occupation of Lincoln. For until they were made effective, it would be impossible to lay the line of the Foss Way between Lincoln and Leicester; and we know from a milestone discovered on that road three miles north of Leicester, and dedicated to Hadrian in A.D. 120 (when he was in Britain), that the eastern part of the Foss Way—doubtless the earliest made in order to connect Lincoln with Watling Street—was being laid down in the first quarter of the second century. In the valley below Lincoln, Ermine Street and the Foss Way, which were united for the crossing, traversed the marshes of the Gap on a pile-foundation. But the chief anxiety of a Roman general, who would secure the submission or tranquillity of this part of Britain, must have been the condition of the Fen district along the lower reaches of the Witham, and beyond it to the south. If the Coritani had to be subdued by force of arms, as we have supposed, their subjugation must have been a long business. Moreover, the Romans were experienced agriculturists, and must have guessed the value of the rich fenland east and south-east of their colony. On that side there was doubtless an even larger mere than on the west—caused partly by the flood-water which had overflowed the Gap, partly by streams from the high land of Kesteven; and this sheet of water must have risen considerably in height during the spring-tides. In this mere for many miles the stream of the Witham must have been barely discernible. Below it the district of Holland was a vast morass, liable to inundation both by the sea and by the rivers—then of much larger volume than now—which fell into the Wash. It is not likely that this district was largely settled by the natives before the Romans came, and the British antiquities found are few; but it was a natural refuge for the disaffected—as was shown later during the Danish and Norman invasions. Herodian says[19] of the campaign in Scotland in 209 that the Emperor Severus made passage for his troops over the fens, where, “from the frequent overflowing of the ocean, the inhabitants will swim and walk, though up to their middle in water.”