Answer:
Although the guns used by the Conquistadors were inaccurate and unreliable, they were still very loud and intimidating. The Incas, who had never seen guns before, likely were scared of the booming sounds and thus more likely to break ranks. On the other hand, the guns used by the Voortrekkers were very accurate, and they could be reloaded and fired quickly from horseback. The guns were so good at killing that the Voortrekkers were able to fend off an attack of several thousand Zulus while maintaining only 3 injuries.
Steel was used by the Conquistadors in their guns and, more importanly, their rapiers, which allowed them to kill many Inca. Steel was used by the Boers for their destructive guns, as well as for their railways, which allowed them to mobilize units and supplies quickly.
Germs worked in favor of the Conquistadors because they had worked and domesticated animals for thousands of years. This created an inherited immunity to their diseases. On the other hand, the Incas had never experienced any of these animals' germs. Thus they were incredibly susceptible to the smallpox germs brought by the Europeans. This is why so many Native Americans were killed by smallpox.
Germs worked against Europeans in Africa because they had not yet been exposed to malaria. They and their livestock had no resistance to the disease, while the Africans had developed antibodies against it for thousands of years. Furthermore, the Africans settled in small communities away from the water, while the Europeans settled close together and near rivers and lakes. This made them incredibly susceptible to mosquitoes and thus to malaria. Finally, the tropical Africans had been raising cows just like the Europeans, and thus were mostly immune to their smallpox.
Step-by-step explanation: