In the wake of the Roman Empire's conquest of Britain in the first century A.D., a large number of troops stayed in the new province, and these troops had a considerable impact on Britain with their camps, fortifications, and participation in the local economy. Assessing the impact of the army on the civilian population starts from the realization that the soldiers were always unevenly distributed across the country. Areas rapidly incorporated into the empire were not long affected by the military. Where the army remained stationed, its presence was much more influential. The imposition of a military base involved the requisition of native lands for both the fort and the territory needed to feed and exercise the soldiers' animals. The imposition of military rule also robbed local leaders of opportunities to participate in local government, so social development was stunted and the seeds of disaffection sown. This then meant that the military had to remain to suppress rebellion and organize government.

Economic exchange was clearly very important as the Roman army brought with it very substantial spending power. Locally a fort had two kinds of impact. Its large population needed food and other supplies. Some of these were certainly brought from long distances, but demands were inevitably placed on the local area. Although goods could be requisitioned, they were usually paid for, and this probably stimulated changes in the local economy. When not campaigning, soldiers needed to be occupied; otherwise they represented a potentially dangerous source of friction and disloyalty. Hence a writing tablet dated 25 April tells of 343 men at one fort engaged on tasks like shoemaking, building a bathhouse, operating kilns, digging clay, and working lead. Such activities had a major effect on the local area, in particular with the construction of infrastructure such as roads, which improved access to remote areas.

Each soldier received his pay, but in regions without a developed economy there was initially little on which it could be spent. The pool of excess cash rapidly stimulated a thriving economy outside fort gates. Some of the demand for the services and goods was no doubt fulfilled by people drawn from far afield, but some local people certainly became entwined in this new economy. There was informal marriage with soldiers, who until AD 197 were not legally entitled to wed, and whole new communities grew up near the forts. These settlements acted like small towns, becoming centers for the artisan and trading populations.

The army also provided a mean of personal advancement for auxiliary soldiers recruited from the native peoples, as a man obtained hereditary Roman citizenship on retirement after service in an auxiliary regiment. Such units recruited on an ad hoc (as needed) basis from the area in which they were stationed, and there was evidently large-scale recruitment within Britain. The total numbers were at least 12,500 men up to the reign of the emperor Hadrian (A.D. 117-138), with a peak around A.D. 80. Although a small proportion of the total population, this perhaps had a massive local impact when a large proportion of the young men were removed from an area. Newly raised regiments were normally transferred to another province from whence it was unlikely that individual recruits would ever return. Most units raised in Britain went elsewhere on the European continent, although one is recorded in Morocco. The reverse process brought young men to Britain, where many continued to live after their 20 to 25 years of service, and this added to the cosmopolitan Roman character of the frontier population. By the later Roman period, frontier garrisons (groups of soldiers) were only rarely transferred, service in units became effectively hereditary, and forts were no longer populated or maintained at full strength.

This process of settling in as a community over several generations, combined with local recruitment, presumably accounts for the apparent stability of the British northern frontier in the later Roman period. It also explains why some of the forts continued in occupation long after Rome ceased to have any formal authority in Britain, at the beginning of the fifth century A.D. The circumstances that had allowed natives to become Romanized also led the self-sustaining military community of the frontier area to become effectively British.

在公元1世纪罗马帝国成功征服不列颠之后，有大量军队驻守在这片新省区，这些军队的军营和城防以及他们参与当地经济都对英国产生了重要的影响。评估军队对人口数量的影响要从士兵在国家内不均匀的分布开始讲起。那些很快就并入帝国的地区并未长期受到军队的影响。而那些保留军队的地区，军队的影响更大。建立军事基地需要征用当地的土地建造要塞，喂养并训练士兵的动物。实行军事统治也强行剥夺了本地领导参与政府事务的机会，因而社会的发展受到了阻碍，由此播下了不满的种子。这就意味着军队不得不维持对反叛的高压政策以及承担组织政府的责任。

因为罗马军队有着强大的消费潜力，经济交流就显得非常重要。在当地，一个军事基地有两种影响，一方面大量的人口需要食物和其他供给。有些食物和供给确实是从远方带来的，但是需求不可避免地由本地承担。尽管这些商品可以强征，但是军队会给予报酬，这些都会刺激当地经济的发展。另一方面当没有战争时，士兵们需要有事可做，否则他们就会成为摩擦和叛变的潜在根源。因此4月25日的一块写字板说一个基地内343名士兵干着诸如做鞋，造浴室，操作炉子，挖泥土和铸铅之类的工作。这样的活动对当地有着显著的影响，特别是基础设施（如道路）的建设使得偏远地区的交通很便利。。

每一个士兵都会有报酬，但是在那些经济欠发达地区花不了那么多的钱。所以这些多余的钱迅速刺激了基地外的经济。一些服务和商品的需求毫无疑问是由外地的人来完成的，但是本地人当然也会卷入到这个新的经济体系中。士兵中出现了非正式婚姻，这种婚姻直到公元197年才得到了法律的承认，从而在这些军事基地周围发展出一些全新的社会群体。这些定居地就像城镇一样，成为了工匠和生意人的聚集地。

军队还为当地征召的后备兵提供了个人升迁途径，一个人从后备队退役之后就可以成为世袭罗马公民。这样的人就是从这些驻地中特别招募而来，并且不列颠的招募规模特别的大。在哈德良皇帝(A.D. 117-138)统治时期总人数至少是12 500人，在公元80年时达到顶峰。尽管这只占总人口的一小部分，但当有大量年轻人离开一个地方时，这可能对当地有非常大的影响。新建立起来的军团通常会被转移到一个不可能回到原籍的省区。大多数不列颠的军团都去了欧洲大陆别的地方，尽管记载下来的只有摩洛哥一个地方。逆过程把年轻人带回英国，在英国很多士兵持续服务20到25年，这样又给驻守边境的人增添了四海为家的罗马情怀。在后罗马时期，前线卫戍部队很少调动，军团中的服务得到了有效的延续，而军事基地也没有人居住或者全力去维持。

这种像群落一样的定居过程持续了好几代，再结合当地的士兵招募大概就是罗马帝国后期英国北部边境比较稳定的原因。这也解释了为什么五世纪初时这些军事基地在罗马已经不再统治英国之后依然存在。这种情况使得本地人罗马化的同时也使得在边境自给自足的军事组织英国化了。