The Time Doctors' Chronicles

Two doctor/scientists transport into the past in an attempt to correct anomalies in the American Revolution and the Civil War, followed then by World War Two - only to be faced later by the Apocalypse and Armageddon. It begins: The British had won the Revolutionary War and America was still a colony. One man is sent back to Valley Forge - the site of the Continental Army's crushing defeat in an attempt the reestablish true history and restore the future. Next, they learn the Civil War had been fought to draw which resulted in two independent American countries, the USA and CSA. One man is sent back in an attempt to neutralize a secret weapon from the future which enabled the South to change the tide against the North's superior war-machine. He returns to now learn Nazi Germany has prevailed in World War Two and rules North America and all of Europe. After a correction with Einstein's help they next find the Earth has suffered a plague which is the Apocalypse and all have perished except Albinos and voracious animals. Finally, the doctors pursue other time travelers who had caused all the previous problems but unexpectedly they, themselves become trapped in a time line of where escaping to the past or future means death by disintegration or going into the flames of Armageddon - the planet's ultimate destruction . They need to devise a correction fast, however...