In London he finds the city completely abandoned and in ruins. He couldn’t find anyone anywhere.
Then he saw one of the Martian Tripods and it made an unnatural noise then stopped and fell. He Climbed it and found a pit with other martians and they mysteriously died.
The Narrator later reveals that the Martians in fact died after being exposed to bacteria and the Aliens had in fact doomed themselves the second they started to breath our air, drank our water, and ate our food.
He finds his wife and life returned to normal and man later aimed to go to the stars.