Red H-Bomb

Overview
What if the Soviets beat the Americans into the first H-Bomb?

Timeline
November 1952: The Ivy Mike thermonuclear bomb fizzles due to unforeseen technical errors. Point of divergence.

August 1953: The Soviet Union successfully tested the world's first hydrogen with their RDS-6 weapon. This shocked the U.S. which began to plan a response to this.

4 October 1957: CCCP launched the first satellite "Sputnik 1".

November 1957: CCCP launched Sputnik 2.

January 1959: The Soviets failed in launching Luna 1 due to technical errors in this TL. Consequently they postponed the Luna program.

June 1959: The U.S. executed a top secret program codenamed "Project A119". An Atlas missile carrying a W25 warhead hit the Moon, causing the explosion to be faintly seen by naked eye and the resulting shock reverberated across the world.

July 1959: Neil Armstrong became the first man in space with the Man in Space Soonest program. He uttered "One small step for me, one giant leap for mankind" during the flight.

October 1959: USSR's Luna 1 became the first object to photograph the far side of the Moon.

May 1960: Joseph Walker became the first man to orbit the Earth. At the same time plans for a military lunar base is being formulated.

April 1961: After a hiatus, the Soviets finally responded by putting Yuri Gagarin into orbit. This hastened the development of the military lunar base dubbed "Project Horizon".

1964: 40 Saturn rockets is launched to prepare for the construction of the moon base. The selected location is the northern part of Sinus Aestuum, near the Eratosthenes crater

January 1965: First cargo deliveries to the lunar location began.

April 1965: The first two men landed on the Moon, one of them is Neil Armstrong, the first man in space.

November 1966: The American lunar outpost is manned by a group of 12 men. Concurrently the Soviets secretly began the development of their military Zvezda base.

March 1971: The CCCP began to ferry supplies to the Moon to build their own outpost.

1974: The Zvezda moonbase is complete.

1983: Stanislav Petrov is absent from his post. Consequently the false nuclear alarm incident turns hot. Billions of people are killed as a result of the nuclear exchange. A Soviet attack on the Horizon moon base is launched simultaneously, which were successfully repelled with Davy Crockett rockets.

2014: As of this year the Horizon moon base is the last remnant of the human civilization.