He was alone when I got there, But they threw rocks from the bridge and when he got to close to "their" side (east) they jumped in and swam out.
It was all over before we got down to the bank.
Threw rocks from the bridge??? the bridge is closed for public gatherings. maybe the french were throwing the rocks, since they were guarding the bridge??
something is missing in your story. think over, and then try again.