Complex sentence: On, it was announced that all six films in the series were to be stereo-converted to 3D, and re-released in chronological order beginning with "The Phantom Menace" which was released on.
Split into simpler sentences: On, it was originally announced that all six films in the series were supposed to be stereo-converted to 3D. The films were supposed to be re-released in chronological order beginning with "The Phantom Menace" which was released on.