Michael was the younger brother of Benjamin IX, who was twelve years his senior, and a member of the Mayhew Clan. Oliver Mayhew was his uncle, Jared Mayhew his cousin, and Bernard Raoul Mayhew his nephew. (HH2, HH11)
Michael was born on Grayson in 1882 PD. He graduated from Anderman University in the Andermani Empire with a bachelor's degree. He hoped to attend a university on Manticore, and was interested in all kinds of naval matters to the point of being considered Navy-mad. In 1903 PD, Bernard Yanakov gave reading material about the Royal Manticoran Navy's Star Knight-class to Michael, who attended a dinner at the Protector's Palace for Captain Honor Harrington.
During the Maccabean assassination attempt on the Protector's life, Michael, who was one of the targets, grabbed his sisters-in-law and pushed them under the table to protect them from gunfire. He survived unharmed.
After the Treaty of Alliance with the Star Kingdom of Manticore was concluded, he went to a Manticoran university to study. As heir to the Protectorship, he was consulted about the impending military action against the People's Republic of Haven. (HH3)
When his nephew Bernard Mayhew was born, he replaced Michael as heir apparent to the Sword. (HH11)