Final answer:
Whites had doubts about African American soldiers' combat effectiveness.
Step-by-step explanation:
One persistent doubt that whites had about African American soldiers in combat was their ability to perform effectively in battle. Some white officers believed that Black soldiers were lazy and lacked purpose in combat, while others argued that Black soldiers underperformed due to racist behavior from higher ranks and limited opportunities for promotion. However, the combat experience of African American soldiers in battles like Fort Wagner and Port Hudson, along with the recognition of fifteen soldiers receiving the Medal of Honor, shattered the white myths of docile and cowardly Black soldiers.