The Symphony in G Major ("Mannheim No. 1") is a Mannheim symphony that was proposed to be by Johann Stamitz, but probably written (but not proven to be) by Antoine Mahaut, a close contemporary of the composer. It was probably written from 1741 to 1746, and if it is truly a symphony by Stamitz, it could be his first. But if it is by Mahaut, it probably is his first. It is formed with the standard 3-movement symphonic scheme of the time:
This symphony, just like the others by Stamitz or Mahaut, definitely influenced Joseph Haydn and Mozart. It is about 7 minutes long.