The Orange River Agreement (referred to as the ORA) is a trilateral agreement between the Cape Colony, the Free States and the United Kingdom. The Agreement was drawn up in the days after the British Empire granted three of its former colonies - the Cape Colony, the Transvaal Colony and the Orange River Colony, substantive autonomy. The UK and many political figures in all three colonies called for a unified country named "South Africa" to be established, including the Natal Colony (which would only receive full independence in 1931). However, the Cape government essentially vetoed this process when it refused outright to join with the "racist, oppressive and regressively-minded Afrikaners to the north", fearing that such a union would violate the Cape's liberal tradition and qualified racial franchise.
With any possibility of union gone, the Imperial government knew that the Transvaal and Orange River Colony (which later joined to form the Free States) will find themselves landlocked. After the Transvaal and the Orange River Colony federated, the Orange River Agreement was drawn up and signed on 10 July 1910, in Colesberg, Cape Colony. Under its provisions, the Agreement gave the Free States full access to the Indian Ocean through the Natal Colony with qualified access through the Cape. However, anticipating that the Natal would be given independence in the near future, a clause was added which obligated the Cape to allow full access rights to the Free States to its ports for trade purposes (with the exception of weapons trade) when, or if the new government of Natal refused to do so. As was expected, one of the first acts of the newly independent Zululand in 1931, was to close its border with the Free States due to its perceived racist policies. The Cape thus was obligated to allow full access.
In return, the Free States was obligated to allow the Cape substantive and far ranging mining rights in the gold fields of the Witwatersrand in the Transvaal. Further, the Cape was granted an exemption to any trade barriers (import or export) or restrictions which the Free States government or its subsidiaries promulgate at any time in the future.
The Agreement was made binding perpetually, and would be enforced by the United Kingdom should one of the other parties violate its obligations.