Complex sentence: Arthur began to devote more of his time to politics and less to law; in 1869, he was appointed counsel to the New York City tax commission under an arrangement his friend Murphy made with William Marcy Tweed, the Tammany Hall boss.
Split into simpler sentences: Arthur began to devote more of his time to politics and less to law. In 1869, he was appointed counsel to the New York City tax commission under an arrangement his friend Murphy made with William Marcy Tweed, the Tammany Hall boss.