The flag of the Orange Free State (1854–1902) was designed in 1856 and adopted officially on 23 February 1857 on the third anniversary of the republic.

The flag of the Orange Free State (OFS flag) was designed by King William III of the Netherlands and (along with other flags of the era) is believed to have been loosely modelled on the United States national flag nd the former South African Republic flag.

The OFS flag was designed by King William III of the Netherlands and (along with other flags of the era) is believed to have been loosely modelled on the United States national flag. The OFS national flag contained alternating horizontal orange and white stripes (three orange and four white, with the white stripes on the outside) with a version of the Dutch flag (used initially by Boer republican movements at Graaff Reinet and Swellendam in 1795) featured in the canton.

The former national flag of South Africa (from 1927 to 1994) had, as a feature contained within its central white bar, a vertically hanging flag of the Orange Free State. Wikipedia