Short answers, pulled from the story.
Somerled died at the Battle of Renfrew in 1164 while campaigning against Malcolm IV of Scotland. This death established the lineage that would become Clan Donald through his son Reginald or Ranald.
A 2005 DNA study revealed that Somerled carried a distinct Y-chromosome R1a1 haplotype indicating Norse descent in his direct paternal line. This finding challenges centuries of tradition claiming the family descended from High Kings of Ireland through Colla Uais and Conn of the Hundred Battles.
Donald of Islay secured Dingwall Castle after defeating the powerful Clan Mackay at the Battle of Dingwall in 1411. Historical records suggest around 10,000 men were present in Donald's army during this conflict before facing Robert Stewart Duke of Albany at Harlaw on the 24th of July 1411.
Thirty-eight unarmed MacDonalds from Clan MacDonald of Glencoe were murdered in 1692 when an initiative to suppress Jacobitism became entangled in long-running feuds. MacIain chief of the MacDonalds of Glencoe arrived late signing an oath of allegiance to William III of England which triggered the charge of slaughter under trust introduced in 1587.
Lord Lyon King of Arms granted undifferenced arms of Macdonald to Alexander Godfrey Macdonald in 1947 making him the first High Chief of Clan Donald. After his death in 1970 he was succeeded by son Godfrey James Macdonald who remains current high chief today.