1939:America feels the continuing effects of the Great Depression. Unemployment remains high and industrial production is low.

Today: The American economy booms: the Dow Jones Industrial Index passes the 10,000 mark, unemployment is at a record low, and inflation is under control.

1939: Europe erupts into full-scale war, pitting Nazi Germany and Italy against France and England. By the year's end, Germany has taken control of Poland, partitioning it with Russia, while Russia has seized Lithuania, Latvia, Estonia, and is preceding in its invasion of Finland.

Today: The conflict in the former Yugoslavia escalates. In the wake of widespread killing, NATO launches a peace-keeping mission and commits to air and ground warfare against Serbia.

1939: Scientists announce that they have succeeded in splitting uranium, thorium, and protactinium atoms by bombarding them with neutrons. Their success paves the way for the invention of the H-bomb in the final...