Complex sentence: Bruce resigned as guardian in 1300 due in part to his quarrels with Comyn, but chiefly because the restoration of King John seemed imminent, and in 1302 submitted to Edward I and returned "to the king's peace".
Split into simpler sentences: Bruce resigned as guardian in 1300 due in part to his quarrels with Comyn, but chiefly because the restoration of King John seemed imminent. In 1302 he submitted to Edward I and returned "to the king's peace".