Complex sentence: Louis died very young, but Francis wrote letters to his mother in Scotland; on 22 March 1545 he sent a piece of string to show how tall he was, and on 2 July 1546 he sent her his portrait.
Split into simpler sentences: Louis died very young, but Francis wrote letters to his mother in Scotland. On 22 March 1545 he sent a piece of string to show how tall he was, and on 2 July 1546 he sent her his portrait.