When Agricola, a wise and equitable Roman ruler, became governor of
Britain he explored the coast, and first discovered Britain to be an
island. He gradually extended the limits of the government, and, in
order to prevent invasion from the north, he built a line of forts
(completed by Antoninus) across Scotland, from the mouth of the river
Forth to the Clyde. (See map facing p. 14.)
From this date the power of Rome was finally fixed. During the three
hundred years which followed, the surface of the country underwent a
change. The Romans cut down forests, drained marshes, reclaimed waste
land, and bridged rivers. Furthermore they made the soil so
productive that Britain became known in Rome as the most important
grain-producing and grain-exporting province in the Empire.