How did Julius Agricola expand Roman control into northern Britain?

As governor of Britain from 77/78 to 84 CE, Gnaeus Julius Agricola significantly expanded Roman control into the northern reaches of the island through a series of strategic military campaigns.

After completing the conquest of Wales and northern England, Agricola moved into Scotland in 79 CE. His expansion efforts included:

• Infrastructure and Fortification: He established a network of roads and built a series of forts in Cumberland and Durham to secure his supply lines and hold the territory.1
• Frontier Establishment: He created a temporary frontier between the Clyde and Forth rivers, guarded by a line of strategic posts.21
• Military Engagement: In 83 CE, Roman forces crossed the Forth and achieved a decisive victory against the Caledonians at the Battle of Mons Graupius.21
• Occupation: He extended Roman influence to the edge of the Highlands, blocking mountain passes with forts and establishing a legionary fortress at Inchtuthil.2

Agricola’s campaigns represented the furthest northern reach of Roman military power in Britain during this period.21