Any expansion is based on interests. For example, nomadic people would rather take risks and invade the rich Central Plains by means of war, and so did Rome, trying their best to conquer the rich areas of Greece and the Middle East! Relatively speaking, Rome attacked Britain across the sea, and Scotland had neither wealth nor tenacious resistance. The Roman Senate will not pay for the expansion of the territory of the Roman Empire to the limit!

Hadrian's accession to the throne coincided with the transition period of the Roman Empire, which was fraught with crises. In the East, the Jewish uprising has just been suppressed, and the situation in Palestine, Egypt and cyrenaica is tense; At the same time, the war between Britain, Mauritania and the lower Danube continued; In addition, in Italy, both urban and rural areas, under the oppression of heavy taxes and corrupt officials, people are brewing resistance. Faced with this situation of internal troubles and foreign invasion, Hadrian decisively adjusted the national military strategy and changed the offensive strategy into a defensive strategy.

In the north of Hadrian's Great Wall, a 60-person fortress is built every 1 1,500 m, and two towers are built between the two fortresses as posts. Once the enemy is found, use fire as a signal, and the army will gather and stand by and fight. On the south side of Hadrian's Great Wall, there is a fortress or fortress every 8,000 meters, including 16, which contains functional buildings such as headquarters, barracks, granaries, hospitals and even temples. It is the core node of Hadrian's Great Wall defense.

Without advanced agriculture, Scotland's land can carry a limited population, and it is not so necessary for settlement. Therefore, Scotland is generally called England's suspension, but if it can be conquered, it will be difficult to rule effectively. This is especially true in Scotland during the Roman Empire. Although we can fight, the army can't find anyone to rule in the mountains. We have to face the harassment and sneak attack of mountain tribes endlessly. It belongs to a place where there is no ruling income but it needs high ruling cost.

Caesar's intention to conquer Britain was not to occupy it, but to deter unstable forces. Coupled with the stability of the Roman civil war and the newly conquered territory, as well as the huge military expenses and serious consumption of soldiers in the expedition, they were not occupied in the end. Even during the Roman Empire, the Romans could only rely on Hadrian's Great Wall to keep the fertile areas in southern England under Roman control, and finally even withdrew from Britain because of serious internal problems.