This name appears to have two derivations, one Highland and one Lowland. The Gaelic, ‘mor,’ is translated as ‘large’ or ‘big’, and the surname may in some instances simply refer to such physical attributes. Alternatively, Muir is also derived from the Middle English for a ‘low grassy hill or heath’. In 1291 Thomas Delamore was executor of the will of Devorgilla, the mother of John Balliol, King of Scots. The chief family of the name were the Mures of Rowallan in Ayrshire. At the beginning of the reign of Alexander III, Sir Walter Comyn seized the house and lands of Rowallan from the Mures. However, the lands were restored after Gilchrist Mure distinguished himself at the Battle of Largs in 1263, when he was also knighted for his bravery. Better relations were established with the Comyns by the marriage of Gilchrist to one of the Comyn daughters, through whom he inherited additional estates. His eldest son, Archibald, was killed at the siege of Berwick when the town was sacked by the English and Balliol’s army routed. The name appears several times on the Ragman Roll of Scottish nobles submitting to Edward I of England in 1296. Sir William Mure, son and successor to Archibald, was knighted by David II, and sent one of his sons as hostage to England for the ransom of the king. His granddaughter, Elizabeth Mure, married the future Robert II in 1346. The validity of the marriage was later challenged, and a papal dispensation was sought to ensure the legitimacy of their children, including the future Robert III. The Mures followed James IV to the fateful field of Flodden in 1513, and many of them died along with their king. Mungo Mure supported his relative, the Regent Arran, during the minority of Mary, Queen of Scots, and fought for him at Glasgow in 1543. He carried out significant improvements to the fine Castle at Rowallan, but was killed at the Battle of Pinkie in 1547. The family embraced the new reformed religion and became opponents of Mary, Queen of Scots, but by the end of the seventeenth century they were persecuted as Covenanters. William Mure of Rowallan allowed conventicles to be held in his house, for which he was imprisoned, first at Stirling Castle and then in Edinburgh. The direct line ended soon thereafter, when the estates passed to the Earls of Loudoun. Another prominent branch of the family, the Mures of Abercorn, prospered under the early Stewarts. A member of this branch, Sir Robert Mure, was one of the jury who tried Lord Ruthven for the murder of Queen Mary’s secretary, David Rizzio. Sir Robert was a favourite of James VI. Alexander Muir Mackenzie, born in 1764, was a descendant of the line of Muir of Cassencarie and was created a baronet in 1805. John Muir, born at Dunbar in 1838, emigrated to America in 1849. He was a naturalist and first advocate of forest conservation in the United States, being responsible for the establishment of the internationally renowned Yosemite National Park.