because america was doing so well and getting so much new territory, the biggest obstacle was themselves. with the new territory, the balance of free and slave states grew tension among american and resulted in the civil war
All their independence was taken away pretty much in WW1. They had no rights or even abilities. This was their main hope, and practically everyone else's, too.
Kabongo uses words and phrases like “dispute among themselves and have no love and” “they have lost laughter” to express that his people have lost their true color and culture.