Complex sentence: In that year King George II issued a Royal Warrant to require each regiment to have, as their first colour the Kings Colour, which was to consist of the Union Flag throughout, as a symbol of its Royal allegiance.
Split into simpler sentences: In that year King George II issued a royal warrant to require each regiment to have, as their first color, the King's color. It was also to consist of the Union flag throughout, as a symbol of royal allegiance.