Will I be able to fight my trespassing fine in court?

I am a soldier at Ft. Sill, OK. During the government shutdown, the Wichita Mts. Wildlife refuge in Oklahoma was shutdown. Because the gate to the refuge was open to vehicle traffic, I assumed the park was open (a lot of it actually was) and I would be able to explore the refuge. I climbed a popular mountain (Mt. Scott) and after I made it to the top and snapped a few pictures, a park ranger (who told me he was not even getting paid) escorted me to the bottom of the mountain and gave me a $225 trespassing citation. There was a small sign at the base of the mountain on the road which I had not noticed because I like to take the path less traveled. The government is supposed to be working for all of us. Not fining us for being active while their own incompetence caused the government shutdown in the first place.