Seventy years ago today on August 14, 1945, the Japanese Empire announced their surrender to the Allies and the end of World War II. The day (August 15th in Japan) is generally known as “Victory over Japan Day” or “V-J Day”. The official Japanese surrender was signed 19 days later on September 2, 1945, on board the battleship USS Missouri (BB-63) in Tokyo Bay.

During the afternoon of this day seventy years ago, joyous Americans took to the streets to celebrate the end of the war. In New York City’s Times Square, a United States Navy sailor grabbed a woman, a “nurse” (she was actually a dental assistant) he didn’t know, and kissed her right in the middle of the street, the moment captured by two different photographers. It is the iconic image of V-J Day and the end of World War II.

Instead of a nurse, it would have been more fitting if he could have kissed a nuclear weapon. The life he later lived was undoubtedly made possible because of them.

Japan’s surrender was expedited by the atomic bombings of Hiroshima (August 6, 1945) and Nagasaki (August 9, 1945). Had Japan not announced their surrender, the United States would have had the next nuclear strike ready for August 19th, and another in September.

Then, still absent Japan’s surrender, Operation Downfall would begin; the invasion of the Japanese home islands in two parts.

November 1, 1945, “X-Day”, was the scheduled date for Operation Olympic, a landing by 14 American Army and Marine divisions in the initial attack on the island of Kyūshū.

Operation Coronet would follow on “Y-Day”, March 1, 1946 – landings directly into the Tokyo plain on the island of Honshū. Twenty-five divisions. Many more would be ready to reinforce them. Many of the Coronet soldiers would have been those retrained and redeployed after defeating Nazi Germany. Victory in Europe wouldn’t have spared them from more fighting to defeat Japan.

All in all, well over two million American servicemen would have taken part in the invasion of Japan. The United States also had plans for the tactical use of nuclear weapons during the attack, anticipating having an additional seven ready bombs on X-Day.

They would have faced a Japanese enemy who correctly predicted where the landings would take place. They would have faced a Japanese enemy who had changed the training for Kamikaze pilots so they would focus on attacking troop transports and landing ships rather than warships.

Estimates of casualties were wide ranging; the Joint Chiefs of Staff predicted in April 1945 that Olympic alone would cost 456,000 casualties, 109,000 of which would be killed or missing in action.

The same study said the entire campaign – Olympic and Coronet – would result in 1,200,000 total casualties, 267,000 killed or missing.

Total American casualties for all of World War II combined: 1,079,162 (407,316 killed/missing and 671,846 wounded). Contemplate that.

Perhaps the best estimate was the number of Purple Heart medals the War Department ordered to have on hand for the invasion: 500,000. Those medals were kept in inventory. They were enough for all the casualties suffered in both the Korean and Vietnam Wars and minor engagements in between and since. They were enough that in 2003, the Department of Defense still had about 120,000 of them remaining in stock from the Japan invasion preparations in 1945. Our servicemen killed or wounded since September 11, 2001 have all been receiving Purple Hearts minted for their grandfathers or great-grandfathers.

And what of the Japanese? Once the Allies landed in the home islands it is very unlikely Japan’s surrender would have happened before the Japanese defenders were largely annihilated.

There were approximately four million uniformed defenders in the Japanese home islands. Based on Japan’s Pacific War record of fighting to the death rather than surrendering, we can surmise that 90 percent or more of them would have been killed.

But that isn’t the real human cost Japan would have suffered. Up to 28 million civilians, including teenage boys and girls, could have been used as militia to resist the invasion. They were armed mainly with improvised weapons like bamboo spears and bomb vests.

They were expected to charge the American invaders in human waves and would have been mowed down and massacred by the tens of thousands.

General Douglas MacArthur’s headquarters estimated that the invasion could cost ten million Japanese lives. Using the 1945 Battle of Okinawa as a benchmark, some also predicted simply that civilian casualties during the invasion of Japan could be similar to Okinawa.

The population of Okinawa before the American invasion on April 1, 1945 was approximately 300,000. The United States Army acknowledges 142,058 civilian deaths occurred during 82 days of combat.

The population of Japan in 1945 was approximately 72 million. If the invasion was indeed similar to Okinawa, that means up to 34 million Japanese civilians could have perished from military action, disease, famine, or mass suicides (as had been seen on Okinawa).

Thirty-four million.

Highest estimate of civilian deaths for all nations during the entire rest of World War II combined, from all causes including the Holocaust? About 58 million.

An invasion of Japan would have been a human slaughter on a scale and ferocity that is entirely incomprehensible. Can you imagine what the mental toll would have been on our servicemen after such carnage?

Total killed by the atomic bombings of Hiroshima and Nagasaki? The high estimate for the two combined is just 249 thousand.

There are today (March 31, 2015) 183,519 Hibakusha – known survivors of either Hiroshima or Nagasaki – still living and recognized by the Japanese government. Only one percent of them (under 2,000) are considered to be suffering from radiation-induced illnesses tied to the attacks.

With those simple numbers, the correctness, the justification, for the United States’ use of nuclear weapons against Japan is settled. We did not save thousands of lives. We saved millions.

If you, the reader, had a relative who was in uniform on August 14, 1945 and would have been involved in the attack on Japan, you might be here reading because the invasion never happened.

If you are Japanese or are of Japanese descent, imagine one-half fewer Japanese today in Japan or elsewhere.

And for all those and the rest of us: nuclear weapons have saved the world from continental- or global-scale war for seventy years. Were it not for nuclear weapons, do you really think we would have gone the entire Cold War without the United States and the Soviet Union getting involved in a direct armed conflict? How many tens of millions would have been killed in that war?

Today, we have a nuclear adversary – Russia – undertaking a strategic modernization while President Obama dreams of a nuclear weapon-free world and thinks militant Islamists like Iran can be trusted to just drop their nuclear ambitions.

Will we make it another seventy years without global conflict and its resulting carnage?

Kiss a nuke today, and hope and pray we do.