Is there any reason that N&W did not pursue a purchase of the Western Maryland? How come N&W did not fight WM's merger with C&O/B&O issuing a bid for it themselves? It seems as a logical purchase for the N&W effectively extending the P&WV subsidiary to Baltimore.
The merger that created Chessie System was a direct result of abortive merger talks(starting in 1965) between N&W and C&O. Had they merged the resulting system would have also included B&O and WM.
The PC bankruptcy sent shock waves through the industry in the Northeast and Mid-Atlantic and the Chessie/N&W proposal died shortly thereafter. IIRC, N&W was perhaps the most solvent railroad in the region at that time and I doubt they would have much desire in the early 1970's Pre-Conrail atmosphere of unease to get into a fight with Chessie and the same regulators trying to figure out how to salvage PC.
I do wonder if the also stillborn "Mid Atlantic Rail-Erie Lackawanna Rail Corporation" merger (basically all the non PC components of Conrail except the Ann Arbor) proposed as a counterweight to Conrail might have included the Western Maryland (and perhaps the D&H and B&M)?