The Northern Expedition began from a base area in Guangdong province. Chiang was able to achieve victory over the warlords in large part because both the National Revolutionary Army and the Kuomintang were far better organized than the warlord armies which they faced. In addition, Chiang had the advantage of a chain reaction affect as victory over one warlord encouraged others to defect to Chiang which strengthened his position even more.
Today, the Northern Expedition is viewed positively both in Mainland China and on Taiwan because it ended a period of anarchy and started the formation of a effective Chinese central government.
See also: Whampoa Military Academy, History of the Republic of China