Michael Haydn's Symphony No. 1 in C major, Perger 35, Sherman 1, MH 23, is believed to have been written in Vienna around 1759. It is not clear whether this is the first symphony Michael Haydn wrote.
Scored for 2 oboes, 2 bassoons, 2 horns, 2 trumpets, timpani and strings, in four movements:
References
Symphony No. 1 (Michael Haydn) Wikipedia(Text) CC BY-SA