It seems that you have missed the necessary options to answer this question, but anyway, I have searched for it and here is the answer. <span>Both european medieval knights and Japanese samurai warriors pledge oaths of LOYALTY TO THEIR MILITARY LEADER. Hope this answers your question.</span>
Read this:
http://www.historyplace.com/unitedstates/vietnam/index-1945.html
They had strong Navy's and had grown strong due to port tradeing