Complex sentence: He also organised a militia named "Highland Watches", calling on members of the landed gentry to sign up and raising the first six companies in 1725 (three of Campbells and one each of Frasers, Grants, and Munros).
Split into simpler sentences: He also organised a militia named "Highland Watches", calling on members of the landed gentry. He raised the first six companies in 1725 (three of Campbells and one each of Frasers, Grants, and Munros).