###Answer the question from the input provided. Please answer from input only.

###Input: Newcastle upon Tyne (RP: i/ˌnjuːkɑːsəl əˌpɒn ˈtaɪn/; Locally: i/njuːˌkæsəl əˌpən ˈtaɪn/), commonly known as Newcastle, is a city in Tyne and Wear, North East England, 103 miles (166 km) south of Edinburgh and 277 miles (446 km) north of London on the northern bank of the River Tyne, 8.5 mi (13.7 km) from the North Sea. Newcastle is the most populous city in the North East and Tyneside the eighth most populous conurbation in the United Kingdom. Newcastle is a member of the English Core Cities Group and is a member of the Eurocities network of European cities. Newcastle was part of the county of Northumberland until 1400, when it became a county itself, a status it retained until becoming part of Tyne and Wear in 1974.[not in citation given] The regional nickname and dialect for people from Newcastle and the surrounding area is Geordie.

The city developed around the Roman settlement Pons Aelius and was named after the castle built in 1080 by Robert Curthose, William the Conqueror's eldest son. The city grew as an important centre for the wool trade in the 14th century, and later became a major coal mining area. The port developed in the 16th century and, along with the shipyards lower down the River Tyne, was amongst the world's largest shipbuilding and ship-repairing centres. Newcastle's economy includes corporate headquarters, learning, digital technology, retail, tourism and cultural centres, from which the city contributes £13 billion towards the United Kingdom's GVA. Among its icons are Newcastle Brown Ale; Newcastle United football club; and the Tyne Bridge. It has hosted the world's most popular half marathon, the Great North Run, since it began in 1981.

The first recorded settlement in what is now Newcastle was Pons Aelius, a Roman fort and bridge across the River Tyne. It was given the family name of the Roman Emperor Hadrian, who founded it in the 2nd century AD. This rare honour suggests that Hadrian may have visited the site and instituted the bridge on his tour of Britain. The population of Pons Aelius at this period was estimated at 2,000. Fragments of Hadrian's Wall are still visible in parts of Newcastle, particularly along the West Road. The course of the "Roman Wall" can be traced eastwards to the Segedunum Roman fort in Wallsend—the "wall's end"—and to the supply fort Arbeia in South Shields. The extent of Hadrian's Wall was 73 miles (117 km), spanning the width of Britain; the Wall incorporated the Vallum, a large rearward ditch with parallel mounds, and was constructed primarily for defence, to prevent unwanted immigration and the incursion of Pictish tribes from the north, not as a fighting line for a major invasion.

Throughout the Middle Ages, Newcastle was England's northern fortress. Incorporated first by Henry II, the city had a new charter granted by Elizabeth in 1589. A 25-foot (7.6 m) high stone wall was built around the town in the 13th century, to defend it from invaders during the Border war against Scotland. The Scots king William the Lion was imprisoned in Newcastle in 1174, and Edward I brought the Stone of Scone and William Wallace south through the town. Newcastle was successfully defended against the Scots three times during the 14th century, and was created a county corporate with its own sheriff by Henry IV in 1400.

From 1530 a royal act restricted all shipments of coal from Tyneside to Newcastle Quayside, giving a monopoly in the coal trade to a cartel of Newcastle burgesses known as the Hostmen. This monopoly, which lasted for a considerable time, helped Newcastle prosper and develop into a major town. The phrase taking coals to Newcastle was first recorded contextually in 1538. The phrase itself means a pointless pursuit. In the 18th century American Timothy Dexter, an entrepreneur, widely regarded as an eccentric, defied this idiom. He was persuaded to sail a shipment of coal to Newcastle by merchants plotting to ruin him; however his shipment arrived on the Tyne during a strike that had crippled local production; unexpectedly he made a considerable profit.



###Question: Newcastle served as a northern fortress for which country during the Middle Ages?

###Answer: {'answer':'England's'}