Complex sentence: Haro's orders were to rejoin Martínez at Monterey, California, but on the way Haro, with support from Narváez and the other pilots, declared his ship no longer under Martínez's command.
Split into simpler sentences: Haro's orders were to rejoin Martínez at Monterey, California. On the way Haro, with support from Narváez and the other pilots, declared his ship no longer under Martínez's command.