Short answers, pulled from the story.
Somerled was a mid-12th-century Norse-Gaelic lord who created the Kingdom of Argyll and the Isles through marital alliance and military conquest. He died in 1164 at the Battle of Renfrew during a seaborne invasion of mainland Scotland.
Somerled confronted Godred Olafsson off the coast of Islay on the 5th and the 6th of January 1156 with 80 ships, following a scheme to place his son Dugald on the throne. After an inconclusive sea battle, the kingdom was divided between Somerled and Godred; two years later, in 1158, Somerled drove Godred into exile and ruled the entire kingdom until his death.
Somerled led a fleet numbered by the Chronicle of Mann at 160 ships against Renfrew, where his forces engaged a smaller Scottish force led by Herbert, Bishop of Glasgow, and Baldwin of Biggar, Sheriff of Lanark. The Carmen de Morte Sumerledi, written by an eyewitness, records that Somerled was wounded by a thrown spear and cut down by the sword at the outset of battle; his son GilleBride was also slain.
Somerled's origins are obscure. He was almost certainly of Norse-Gaelic ancestry, and his father's name, GilleBride, and grandfather's name, GilleAdamnan, are corroborated in Irish annals. Genetic studies published in 2004 and 2011 found that his patrilineal marker belongs to haplogroup R1a, very common in Norway and extremely rare in Celtic-speaking Scotland, suggesting his patrilineal ancestors originated in Scandinavia.
Genetic studies suggest Somerled may have close to 500,000 living patrilineal descendants. A 2004 study found shared genetic markers among chiefs of Clan Donald and in samples of MacAlister, MacDougall, and MacDonald men; a 2011 study of 164 men bearing the MacDonald surname found 23% carried the same marker as the clan chiefs.
In 1164, the year of his death, Somerled attempted to persuade Flaithbertach Ua Brolcháin, Abbot of Derry and head of the Columban monastic community, to relocate from Ireland to Iona. Iona's oldest surviving building, St Oran's Chapel, which dates to about the mid-12th century, may also have been built by Somerled or his family.