This article is from the Anime FAQ, by Steve Pearl with numerous contributions by others.
Sherman, set the Way-Back machine to 1982, in Japan. It was then that a series by name of Super Dimension Fortress Macross first aired on Japanese television, a product of Tatsunoko.
After Macross ended in 1983, Tokyo Movie Shinsha's Super Dimension Century Orguss took its place on the airwaves. Orguss shared some common creators with, and had a few in-joke references to Macross. Beyond that, there was no relation. When Orguss finished its run of episodes, another "Super Dimension" show took its place: Super Dimension Cavalry Southern Cross. This is also in 1983. Bear in mind that these "Super Dimension" shows had little in common save the title. They were not related in any way, save for the brief references in Orguss mentioned above.
Megazone 23, one of the first OVAs (Original Video Animation), was released in 1984. It had the same character designer as Macross and Orguss, one Haruhiko Mikimoto. On television, a short-lived series by name of Genesis Climber Mospeada came and went. Theatrically, the Macross movie was released (its title, Macross: Oboete Imasuka has been translated as Macross: Love, Do You Remember? or Macross: Do You Remember Love). The Macross movie was more of a retelling of the Macross series, rather than a sequel.
Let's wander over to North America. Sometime around mid- to late 1984, the rights to the Macross series were acquired by Harmony Gold. Originally, Macross was slated to be translated rather faithfully, and a TV-movie compilation of the first three episodes had been broadcast. However, the "golden number" for television syndication is 65 episodes - 13 weeks of daily weekday episodes. So, in order to pad out the series, Macross was reworked a little, Southern Cross and Mospeada were hastily adapted and tacked on to the end, and the 85-episode Robotech series was born, first aired in 1985. (An extra transition episode was created by editing footage from Macross and Southern Cross together.)
Now things get a little murky. Sometime around 1985-1986, back in Japan, Shogakukan commissioned an English translation of the Macross movie, which was then titled Super Space Fortress Macross. Also, Megazone 23 Part II was released on video.
In 1986, Macross Flashback: 2012, a 30-minute OAV, was released in Japan. This was 22 minutes of scenes from the Macross series and movie, as well as images from various Macross publications, edited to accompany music from the series, plus eight minutes of new animation, showing some footage previously cut from the movie, as well as a showing what happened to our heroes after the war. Back in the US, Harmony Gold was riding the crest of Robotech's popularity, and had started production on Robotech II: The Sentinels and a Robotech movie. Sentinels was to be a brand-new series of 65 episodes, written in North America and animated in Japan, for North American broadcast. For a variety of reasons, this was never completed, and as a consequence never released on television. The Robotech movie was a re-edited Megazone 23, combined with footage from Southern Cross, plus a 12-minute happy ending, comprised of new animation commissioned from Japan. The movie was barely released (a few test screenings and a showing at the Los Angeles Animation Celebration) before vanishing from the big screen altogether.
Back to Japan: Megazone 23 Part II is translated to English with Japanese subtitles, for use as a Japanese teaching aid. The 12 minutes of new footage for the Robotech Movie is included on this video, which was released as Megazone 23 Part II: Foreign Edition.
A quick hop back to North America - in 1987, Super Space Fortress Macross makes it to North American shores - minus 18 minutes of footage - as Clash of the Bionoids.
In 1988, seventy-six minutes of completed footage from Sentinels was compiled and released on video.
In 1992, Macross II - a sequel to the Macross movie - is released nearly simultaneously in Japan and the United States.
--From a posting by Emru Townsend