Complex sentence: The temporary route operated successfully, quickly becoming one of the main avenues of trade between New York City and San Francisco, but a civil war in Nicaragua and an invasion by filibuster William Walker intervened to prevent the canal from being completed.
Split into simpler sentences: The temporary route operated successfully, quickly becoming one of the main avenues of trade between New York City and San Francisco. Civil war in Nicaragua and an invasion by filibuster William Walker intervened to prevent the canal from being completed.