The answer is a strong central government
Segregation in the United States Armed Forces was required by Jim Crow laws.
The Jim Crow laws were state and local laws in the United States, promulgated by the white state legislatures, that at the time were dominated by the Democrats after the Reconstruction period between 1876 and 1965. These laws advocated the racial segregation in all public facilities by de jure mandate under the slogan "separate but equal" and applied to African-Americans and other non-white ethnic groups in the states of the United States. In reality, this led to treatment and accommodation being generally inferior to those insured for American whites, systematizing a number of economic, educational and social disadvantages. The de jure segregation was applied mainly in the southern United States. On the other hand, in the north, segregation was generally de facto predominantly towards blacks who lived in urban ghettos.
Some examples of Jim Crow laws were segregation in public schools, public places, public transportation and the segregation of bathrooms and restaurants; In addition, there were also sources of drinking water for whites and blacks. The US military was also segregated. The Jim Crow laws were derived from the black codes (1800-1866), which had also limited the civil rights and civil liberties of African-Americans.
The main cause of the rise of caudillos in Mexico was wide-spread political disorder and a lack of a sufficient power structure following revolutions, since these military leaders used this lack of order to seize power.
