This movie was based on the true story of the naval engagement and of course, with the location, commanders' name and the units involved changed.
However, the movie is not 100% accurate in the battle scene in that the actual battles, both sides used World War II era and pre-World War II era British gunboats, some of which were directly sold to China, while others were first sold to Australia and then later transferred to China after the end of World War II.
At the time this movie was shot, those gunboats were undergone refit so Soviet gunboats were used instead. The sailors who were in the actual battle expressed their concern about this because Soviet gunboats and British gunboats look very different, but the film crew refused to use models instead because they wanted a realistic scene of big picture, i.e. shot in the real ocean, instead of concentrating on what they considered 'small dissimilarity'.
Before the reform in China, information was not readily available to public so this did not appear to be a problem, but after the reform, the general public can easily get the information on military hardware previously considered 'secrets' and even the least experienced military enthusiasts could identify this flaw, so when the movie was re-released and re-issued on DVD, many complained its fake.
