Germany had a much smaller sized fleet than UK, it is why they were unable to launch an invasion. Their air force also failed to completely knock out the UK air force during the Battle of Britain. What if Japan had sent their carrier fleet to Germans' aid to help them conquer UK. Do you think UK could have stood a chance against the level of fleet that Japan had pulled off at Pearl Harbor and Midway? They had over 200 surface ships and 700 carrier planes at the Battle of Midway. If they throw this fleet at UK during the time of Battle of Britain... With Japanese naval and air force support, do you think Germany could have been able to conquer UK? From that point on, what do you think would have happened afterward?