4. Why is it ironic that the 9th Cavalry of the Buffalo Soldiers were tasked with securing the

road from San Antonio, Texas to El Paso, Texas from the Native Americans?

The irony behind the 9th Cavalry of the Buffalo Soldiers being tasked with securing the road from San Antonio, Texas to El Paso, Texas from the Native Americans was that:

They were African Americans another minority group frustrated by abuse and broken promises by the U. S. Government.

Explanation:

To understand this answer we need to analyze the context. The Buffalo soldiers were African American soldier that had fought in the civil war. They had fought two governments and had let down by the government that liberated them by breaking its promises, as well as keeping discrimination after breaking the slavery. Therefore, the fact that they were tasked to suppress another minority exhausted and frustrated by the society's discrimination and the government broke promises was ironic.