The War ended on March 29, 2049 when the last Earthian troops surrendered to the Venusian peace forces.
When did the War begin? The first battle was fought on December 18, 2048, but the first 'incident' that led directly to the conflict occurred in November, 2042. And even before that date, many years before, officials on Venus knew that war between the two worlds was inevitable.
We bid you welcome, Earthmen! Take your rightful place beside us, share our peaceful existence. By your endless struggles you have earned it.