1. On June 15, 1864, the Second Battle of Petersburg began during the American Civil War. The battle was fought for nine months and was a significant turning point in the war.

2. In 1904, The Spokane and Eastern Railway started operations between Naches and Yakima. The railway was essential in connecting the eastern region of Yakima County to other parts of the state.

3. On June 15, 1916, the Boeing Company was founded in Seattle, Washington. Today, Boeing is one of the world's largest aerospace companies and a major contributor to Washington's economy.

4. In 1958, the world's first nuclear-powered submarine, the USS Nautilus, arrived in Puget Sound, Washington. The submarine played a vital role in the Cold War and paved the way for nuclear-powered ships in the Navy.

5. On June 15, 1991, Mount Pinatubo, a volcano in the Philippines, erupted and sent a plume of ash that reached as far as Washington state. The ash cloud caused a temporary halt to air travel and affected crop production in the state.