Final answer:
The atomic bombings of Hiroshima and Nagasaki led to Japan's unconditional surrender and the end of World War II in 1945
Step-by-step explanation:
The main effect of the atomic bombs dropped on Japan during World War II was the surrender of Japan to the Allies, which subsequently led to the end of the war. Following the atomic attacks and the invasion of Manchuria by Soviet forces, Japan was under immense pressure. The Japanese government agreed to the Allied terms of surrender on August 10th, and Emperor Hirohito officially endorsed the decision on August 15th. The formal signing of Japan's surrender aboard the USS Missouri on September 2 concluded the conflict.
Debate surrounds the use of the atomic bomb, with various arguments about whether the bombings were strictly necessary or were influenced by other factors, such as sending a message to the Soviet Union. However, what is clear is that the bombings of Hiroshima and Nagasaki had a decisive impact, leading to Japan's surrender without the need for a bloody invasion, which was estimated to potentially cost hundreds of thousands of Allied lives.