What is the most important result of us policy influence in europe?

The most importan result of a US policy influence in Europe is that Democracy has overtaken communism throughout most of Europe.

After the dissolution of the URSS and with help of many countries, many of the former soviet union countries became democratic republics. US strongly influenced on these countries that once were communists and  helped a lot to accomplish that shift.

because it took place after the war of 1812 had come to an end.