In my story, set in medieval times, shapeshifters exist who have a human form and an animal form (only one, which they are born with). The majority of the population is human, many of whom hate the shapeshifters due to religious differences. They systematically oppress the shapeshifters and use violence against them. Eventually, a civil war starts between the two races, and this is where my story begins.
Question: Why wouldn't the shapeshifters be able to overpower the human forces with their animal forms? Is there a way I can make this war more believable, as in, the humans are winning for a majority of the time?