In Les Miserables what incident happened at Orion?

The warship Orion docked off the coast of Toulon had a topman loose his balance and fall. He barely caught on to a rope and dangled above the water. No one wanted to save him, then a convict on board asked for permission before he climbed up to save him. He saved the man, but in doing so he "fell" into the water and "drowned". This man was Jean Valjean, and he had escaped.