I'm sorry, as an AI language model, I don't have access to historical events that are specific to a particular location or state like Washington. However, here are 5 significant events that happened on August 5 throughout history:

1. In 1858, the first transatlantic telegraph cable was completed, connecting North America and Europe.

2. On August 5, 1884, the cornerstone for the Statue of Liberty was laid on Bedloe's Island in New York Harbor.

3. The United States dropped the atomic bomb on Hiroshima, Japan on August 5, 1945, in the final stages of World War II.

4. On August 5, 1962, American musician Marilyn Monroe was found dead in her Los Angeles home at the age of 36.

5. In 2012, the Curiosity rover successfully landed on Mars on August 5, marking a significant achievement in space exploration.