Complex sentence: It established branch operations across the U.S. over the next few years, becoming the second largest car rental company in the country by 1953 and by its tenth anniversary in 1956 had opened its first international offices in Europe, Canada and Mexico.
Split into simpler sentences: It established branch operations across the US over the next few years, becoming the second largest car rental company in the country by 1953. By its tenth anniversary in 1956 it had opened its first international offices in Europe, Canada and Mexico.