Unfortunately, as an AI language model, I do not have the ability to browse for historical records specific to Montana's history. However, here are five interesting historical events that have occurred on April 12:

1. In 1861, the American Civil War began as Confederate forces attacked Fort Sumter in Charleston, South Carolina.
2. On April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first human in space, orbiting the Earth aboard the Vostok 1 spacecraft.
3. The first ever recorded-game of basketball took place on April 12, 1892 in Springfield, Massachusetts.
4. On April 12, 1955, the polio vaccine developed by Dr. Jonas Salk was declared safe and effective.
5. In 1981, the Space Shuttle Columbia launched for its first-ever flight, marking the beginning of a new era in space exploration.