Union Flag of Hulstria and Gao-Soto

The Union Flag of Hulstria and Gao-Soto also known as the Unity Flag was the national flag of Hulstria and Gao-Soto during the Septembrist era. Designed originally in 3386 to represent the unity of the preceding Imperial Crownlands of Hulstria and Gao-Soto after the institution of the new dual monarchy, it was adopted as an important national symbol by the 15th of September Movement during the September Revolution and afterward returned as the national flag of the Crownlands. With the exception of the first flag of Mikuni-Hulstria, all subsequent national flags have employed its basic white-purple-green colour scheme, though modifying or removing the simple unified coat-of-arms in the canton.

Due to its association with the long-standing Septembrist era, the Union Flag has been adopted as a symbol of the 15th of September Movement and served as the national flag of the two Septembrist provisional governments that have since been declared, although it has not, at this point, returned as the official national flag.

Symbolism
The Union Flag was intended to symbolise the unity between the Empires (under later Septembrist interpretation the peoples) of Hulstria and Gao-Soto, represented by the incorporation of their traditional coats of arms into a single simple version of the national coat of arms and, more prominently, by their national colours, purple and green respectively. The white bar at the top of the flag has a practical use avoiding the placement of one of the national colours in the canton. However, the white bar symbolises the unity between the two nations and the snow-capped peaks of the Schnee-Berge Mountains which dominate the Crownlands as well.