LITCHFIELD — Author, historian and state representative Dean Urdahl will unveil his most recent film, "Assault on Fort Ridgely," based on his 2008 book, "Uprising," at 7 p.m. April 23-25 at the Hollywood Theater in Litchfield. Due to the subject matter and the sheer scope of the project, Urdahl and his team opted to produce three films instead of one. As a result, all three films were being shot simultaneously starting last year. Urdahl’s debut film, “Uprising,” came out last year.