This just continues the misunderstanding between Real-Time-Tactics and Real-Time-Strategy.

RTT is where you send units out to some location and micromanage each battle out. Most of the "RTS" games are really only RTT, and that's what you're really talking about.

RTS means you send units out to some location and let them sort it out while one plans the bigger picture of the war -- not the individual battles. This is backed up by the dictionary and strategics:
the science or art of combining and employing the means of war in planning and directing LARGE military movements and operations

While tactics are: the art or science of disposing military or naval forces for battle and MANEUVERING them in battle

Also, Herzog Zwei predates Dune II and better qualifies as one of the first of these RTT games.