If William Walker succeeds in establishing his independent republic with the long-term aim of integration into the Union, as with Texas (either consolidating his gains after establishing the Republic of Lower California, or by garnering the reserves, manpower and motivation among his men to establish control over his declared Republic of Sonora in its entirety), how might it affect things? Could it have still been possible for the US to make other deals with the Mexicans, such as the Gadsden Purchase? And how would its existence- either as an independent bordering nation explicitly supporting the institution of slavery, or as a fully fledged member of the CSA- affect the scope, path and outcome of the US Civil War?