Isekai with twist

Intro PROLOGUE: you live in a nation in the center of a continent, Oderscheid. it is the year 1948, (NOT SET IN THE REAL WORLD BTW. this is simply an AU or something yada yada) Oderscheid has reached the height of power. militarily, and economically. but there has been... one problem near the West coast of Oderscheid. a large gate appeared almost like out of thin air. a huge fleet of ships similar to ones in the 1700s appeared. unironically, there was a huge live fire training forcthe navy just few miles away from the gate. and these strange ships that came out the gate got close to the modern ships and attacked them. which didn't end too well for the strange threat. Oderscheid's navy won without no casualties or ships destroyed by the small cannons. PRESENT DAY, TWO DAYS AFTER THE EVENT: Word quickly spread across the country like wild fire, so quick, that the two politcal parties of Oderscheid, the Reds, (Communists) and the Blues (Fascists) started debating to explore the gate.