Complex sentence: When the election was held in February 1855, Seward won a narrow majority in each house, though the opposition was scattered, and a Know Nothing party organ denounced two dozen legislators as "traitors".
Split into simpler sentences: When the election was held by the legislature in February 1855, Seward won a narrow majority in each house. The opposition was scattered, and a Know Nothing party organ denounced two dozen legislators as "traitors".