Complex sentence: During his term as state senator, Seward traveled extensively, not only going to visit other anti-Jackson leaders, including former president Adams, but also accompanying Samuel Seward on a trip to Europe, where they met the political men of the day.
Split into simpler sentences: During his term as state senator, Seward traveled extensively, going to visit other anti-Jackson leaders, including former president Adams. He also accompanied his father Samuel Seward on a trip to Europe, where they met the political men of the day.