Complex sentence: The union negotiated a groundbreaking agreement in 1960, that permitted the extensive mechanization of the docks, significantly reducing the number of longshore workers in return for generous job guarantees and benefits for those displaced by the changes.
Split into simpler sentences: The union negotiated a groundbreaking agreement in 1960, that permitted the extensive mechanization of the docks. Its leadership agreed to significantly reducing the number of longshore workers in return for generous job guarantees and benefits for those displaced by the changes.