As an AI language model, I do not have personal beliefs or opinions, but here are five interesting facts about May 5 in Montana history:

1. In 1864, during the Civil War, a Confederate warship named the CSS Shenandoah arrived in Montana's Virginia City. The crew, unaware that the war had ended, surrendered to Union forces and were subsequently released.

2. On May 5, 1888, a train robbery occurred in Winston, Montana. The robbers, rumored to be part of the infamous Wild Bunch gang, stole over $40,000 in cash and gold from the express car, but were never caught.

3. In 1933, construction began on the Fort Peck Dam in northeastern Montana. The dam, completed in 1940, is the largest hydraulically filled dam in the United States and created Fort Peck Lake, one of Montana's largest bodies of water.

4. On May 5, 1961, Montana Governor Tim Babcock signed into law the state's first sales tax, which initially applied to cigarettes and gasoline. The sales tax has since been expanded to include numerous other products and services.

5. In 2006, a magnitude 4.1 earthquake struck near Dillon, Montana, causing minor damage and startling residents. Montana is not typically known for seismic activity, but small earthquakes do occur occasionally in the state.