The world leader, in fact. However, as the market for dedicated word processors petered out, Wang upgraded the word processor hardware, added some form of OS (dunno exactly what that was), bundled their word processing package and sold the whole shebang as a "general purpose" computer that also happened to support the leading word processor of the day. IIRC, the thing was non standard in both hardware and software, and very expensive compared to the Apple ][ and that newfangled IBM PC that was just starting to hit the market at the time. Also, a company called AMI released software for the PC called, appropriately "Ami" that worked just like the Wang word processor software. Would even read Wang WP disks, IIRC. That was basically the death of the Wang as a market player.

[edit: typos, what else?]