The best defense is a great offense and the Uesama had one of the successful armies during Sengoku Japan. In fact, it was revolutionary at the time. The Shogun Yashiki at the Samurai archives has an excellent article on how Nobunaga was able to divide his army to fight several fronts. The article explains the military concept the principles of the Objective, Offensive, and Mass.
The Shogun Yashiki: "Nobunaga was truly the first samurai commander to divide his operations into theaters, with Hideyoshi commanding his forces in western Japan, Shibata Katsuie commanding Oda forces in the north, Sakuma Nobumori leading forces against the Ishiyama Honganji in central Japan, and Tokugawa Ieyasu (as a subordinate ally) in charge in the Tokai region to the east. Nobunaga never ceased being on the offensive--he would move between theaters with his main army to exploit offensive opportunities created by his subordinate commanders. When an objective in one area was reached he would shift focus to the next offensive opportunity--for instance, when the surrender of the Ishiyama Honganji was finalized, he shifted focus to the final destruction of the Takeda in Shinano and Kai."
The link to the article is here:http://www.shogun-yashiki.blogspot.com/2012/08/greetings-once-again-samurai-archives.html
His success was a key to location as well. As stated in an earlier post, Azuchi was the perfect place for the Uesama to launch a full scale attack anywhere. For his enemies, it must have been a horrified experience to see the Oda army always on the offense. If there was one drawback, he almost stretched his forces too thin as he was killed at the Honnoji in 1582 due to betrayal. There was nobody nearby to to defend him. However, this skill of dividing his army to be able to fight on several fronts successfully made him a genius.
Nobunaga no tame!