With his health continuing to deteriorate, the Black Prince returned to England in January 1371, whereby now his father Edward III was elderly and also in poor health. The prince's illness was debilitating, and he died on 8 June 1376. Edward III died the following year on 21 June 1377; he was succeeded by the Black Prince's second son Richard II , who was still a child. The treaty at Brétigny left Edward III and England with enlarged holdings in France; however, a small professional French army under the leadership of du Guesclin pushed the English back and, by the time of Charles V's death in 1380, the English only held Calais and a few other coastal cities. It was usual to appoint a regent in the case of a child monarch, but no regent was appointed for Richard II, who nominally exercised the power of kingship from the date of his accession in 1377. However, between 1377 and 1380, actual power was in the hands of a series of councils. The political community preferred this to a regency led by the king's uncle, John of Gaunt, although Gaunt remained highly influential. Richard faced many challenges during his reign, including the Peasants' Revolt led by Wat Tyler in 1381 and an Anglo-Scottish war in 1384-1385. His attempts to raise taxes to pay for his Scottish adventure and for the protection of Calais against the French made him increasingly unpopular.
Question: How many years did the Anglo-Scottish war last?
Answer: 1