Complex sentence: Joseph "Joe" Cartwright was an English professional rugby league footballer who played in the 1920s, playing at representative level for Great Britain, and England, and at club level for Leigh, as a, i.e. number 9, during the era of contested scrums.
Split into simpler sentences: Joseph "Joe" Cartwright was an English professional rugby league footballer who played in the 1920s. He played at representative level for Great Britain, and England, and at club level for Leigh, as a, i.e. number 9, during the era of contested scrums.