In "Themes: Exile," we mentioned that humans have been displaced from their position at the top of the food chain by the Martians. How did the Martians displace humanity? Well, they were simply too powerful for the humans to beat. Now, although the Martians might seem to be the most powerful creatures on Earth, there are several examples in The War of the Worlds of humans using power against other humans, such as the robbers who attack the Elphinstones. And then there's the final kicker: sure, the Martians are very powerful, but what good does it do them when they forget their anti-bacterial hand sanitizer? When what seems to be most powerful being gets knocked off by what seems to be least powerful, well, then we might have to question our whole notion of power.
While war seems central to this novel, Wells is mostly interested in how power is behind every relationship. For instance, even though his wife doesn't want him to leave Leatherhead, she doesn't have the power to stop him, because at that time, husbands would be assumed to have more power in the relationship.
While Wells is interested in what power does to human actions, the ultimate power here is not the Martians' power or the bacteria's power, but the power of the laws of nature. In other words, evolution is even more powerful than the Heat-Ray.