The Roman defence of Britain
Why did Hadrian build his wall?
When the Romans invaded Britain they had to defend it against constant attack from Celtic tribes. To do this, they built forts around Britain for the soldiers to live in. At first they were built of wood, later they were built of stone.
The threat from Scottish Barbarians grew, and in 122 A.D. the Emperor Hadrian ordered his soldiers to build a wall between Roman Britain and Scotland. The wall ran from Wallsend to Bowness on the Solway Firth, and you can still walk along parts of it today.
In the third century A.D. the wall was broken and the Emperor Septimius Severus had to come to Britain to fight against tribes invading from Scotland. Although his soldiers won the battles he died at York in 211 A.D.
Why did the Romans build roads?
When there was trouble soldiers needed to march from one part of the country to another quickly. As a result the Romans built proper roads instead of muddy tracks because they were easier to walk along. This also made travelling around Britain easier for everyone. You can still see the remains of some Roman roads today.
How did Roman Britain defend itself from foreign invasion?
Because Britain was on the edge of the Roman Empire there was often trouble from people trying to invade. Pirates would often attack, so forts were built on the coast.
If the pirates got past the Roman navy then soldiers keeping watch at the new forts would raise the alarm and go out to fight them. They are called Saxon Shore forts because many of the people attacking Britain at this time were Saxons. The Saxon Shore fort at Portchester was so big that hundreds of years later people built a whole castle in just one corner of it!
http://www.bbc.co.uk/schools/romans/defence.shtml