A example of this is the Russia-Ukraine War. When Russia invaded Ukraine last year, everyone thought that within a week, Russia will wipe out Ukraine. Because the Russian army is much larger than the Ukrainian army. And more advanced, technologically. But the motivation levels among the Ukrainian soldiers were much higher. This is why, till date, Ukraine has been quite successful in defending itself.
Battle of Britain Day was one of the first major losses for Hitler. For the first time in World War 2, Hitler faced loss. Hitler knew that there was little chance of this mission being successful so Operation Sea Lion was postponed. And Hitler shifted his focus from the UK to the Soviet Union.
