Complex sentence: In 1852 the Leeds Northern Railway reached Stockton, made an alliance with the NY&BR's competitors and a price war broke out, the fare for between Leeds and Newcastle dropping to two shillings.
Split into simpler sentences: In 1852 the Leeds Northern Railway reached Stockton, and made an alliance with the NY&BR's competitors. In a price war, the fare for between Leeds and Newcastle dropped to two shillings.