The flag of Haydn was adopted in May of 1645 by Emperor Haydn VI. Many of the changes made by Haydn VI changed the course Haydn would go, the flag being one of them. Haydn VI first saw it in 1643, when a flag maker by the name of Ultrad Johnson had it flying outside his house in Haydnberg. He called for a meeting with Johnson, where they discussed the terms of having his flag the national one.
The flag of Haydn was finally made the national one in May, of 1645, when Johnson and Haydn VI came to agreements. It is stated that in the Leges Imperial Empire de Haydn, that the Emperor can change the flag at any time. The flag serves as a national flag, and civil and state ensign.