Complex sentence: In 1921, the WB&A also acquired the Baltimore & Annapolis Short Line, after which the AW&B trackage was termed the South Shore Division and the Short Line the North Shore Division.
Split into simpler sentences: In 1921, the WB&A also acquired the Baltimore & Annapolis Short Line. After the acquisition the AW&B trackage was termed the South Shore Division, and the Short Line was called the North Shore Division.