Dune 2 is the first RTS ... by westwood..
Blizzard was next with warcraft.. which added "groups" and a bunch of other stuff.. (yeah u couldnt select 2 units in dune2 AFAIK .. i remember lining up my units in a huge line and then clicking each one .. pressing M and then clicking somewhere on the map so that the lined moved .. one by one)
C&C came after by westwood.. for the sole reason that the Dune license was limited to 2 games.. (C&C is basically dune3)
then starcraft .. again by blizzard ...
I'm not mentioning sequels because i really dont remember when warcraft 2 and stuff came out..
but yeah .. quake1 was huge.. i was big into console manipulation and making mods with quakec... maps that had "brushes" just because quake didnt have concave 3D objects.. (you had to break it down to convex objects called "brushes")
We just played medal of honor multiplayer and i used my console skills there too
edit: I should have said dune2 was my first RTS