In this timeline during the 2.schleswig war in 1864 the danish fights the prussians all the way to northern germany were the prussians surrender. Denmark annexed all of northern germany and poland and reforms into the danish empire. 10 years later the danish empire invades sweden and norway. It is a total success and the danish empire annexed norway and sweden.
But the the “allies” of the danish empire (russia,france and england) which nearly helped denmark in the real timeline but chose not to. Said that denmark has gone too far and and that if denmark does not free norway and sweden then there will be war. Denmark keeps norway and sweden and goes to war so starts this timelines ww1. The way superior danish navy crushes the british and invades britain. Denmark wins and dismantles the united kingdom into Scotland,Wales,ireland and england and takes all of the french and british colonies. Denmark signs a peace treaty with russia. Which gives denmark finland and makes the russian side of the russian-danish border a demilitarized. Denmark also goes to war with the usa and takes some of northern usa. Two super powers also rises in south america the empire of brazil and the people's union of argentina with regularly goes to war. In 1900 the communists takeover in russia and creates the soviet union with lenin as its leader. in 1930 the soviet union breaks the peace agreement. Denmark prepares an invasion and it is ready in 1945. Mean while they were preparing the invasion the danish has been researching into jet fighters, rockets and most importantly nuclear weapons. So on the 1.st of july the Danes strike nucking moscow and swiftly wiping out the russian air force. The danish dropped paratroopers in leningrad, stalingrad and kiev and launches a ground offensive one year later russia surrenders. Then the Russian Republic was put in power in russia.
In 1960 the danish successfully put the first person on the moon.
Today The Danish Empire has colonies on the moon and planning to send people to mars and are nearly fully independent on fossil fuel and nearly makes no pollution