Complex sentence: Two hours from their destination, however, on the 24th June/7th July, a wave severed the towline; but the "Ismail" stayed with the Potemkin until it reached port the next day.
Split into simpler sentences: Two hours from their destination, on the 24th June/7th July, a wave severed the towline. The "Ismail" stayed with the Potemkin, however, until it reached the port the next day.