兵家; School of Military & 縱橫家/纵横家 School of Diplomacy

The Warring States Period saw the introduction of many innovations to the art of warfare in China, such as the use of iron and of cavalry. Near the beginning of the Warring States Period we see a shift from chariots to massed infantry, possibly associated with the invention of the crossbow. This had two major effects. First it led the dukes to weaken their chariot-riding nobility so they could get direct access to the peasantry who could be drafted as infantry. This change was associated with the shift from aristocratic to bureaucratic government. Second, it led to a massive increase in the scale of warfare. The bloodshed and misery of the Warring States Period goes a long way in explaining China's traditional preference for a united monarchy.

The Warring States was a great period for military strategy. The military strategist Sun Tzu is said to have written The Art of War, which is recognized today as the most influential and oldest known military strategy guide. Along with this were other military writings that make up the Seven Military Classics of ancient China: Jiang Ziya's Six Secret Teachings, Sima Rangju's The Methods of the Sima, Sun Bin's Art of War, Wu Qi, Wei Liaozi, Three strategies of Huang Shigong, and Questions and Replies between Tang Taizong and Li Weigong (the last being made approximately 800 years after this era ended).

孙子兵法 – Art of War by Sun zi

知彼知己，百戰不殆；不知彼而知己，一勝一負；不知彼，不知己，每戰必殆
If you know your enemies and know yourself, you will not be imperiled in a hundred battles; if you do not know your enemies but do know yourself, you will win one and lose one; if you do not know your enemies nor yourself, you will be imperiled in every single battle.

“兵者，诡道也。 All warfare is based on deception”.

Indeed, Deception is that Art.

Along with the Strategic school we can mention the School of Diplomacy, as one of main Chinese School of Thought. This school focused on practical matters instead of any moral principle, so it stressed political and diplomatic tactics, and debate and lobbying skill. Scholars from this school were good orators, debaters and tacticians The few principal written records of the School of Diplomacy that exist today are the thirteenth chapter of the 'Book of Gui' or 'Gui Gu-zi', the thirty-third chapter of 'Annals of the Warring States Period' (not about the School of Diplomacy’s followers but primarily the words and actions of its advisors as well as actual combat case studies), the thirty-first chapter of 'Su Zi' and the tenth chapter of 'Zhang Zi'. The seventh chapter of the 'Benjing Yifu' appendix to the 'Gui Gu-zi' describes the mental and moral cultivation methods used by the School of Diplomacy; the 'Benjing' covers the ideas behind the basic guiding principles whilst the 'Yinfu' consists of very mysterious concealed writings. The reader can comprehend these but is unable to discover their essential meaning. The 'Gui Gu-zi' is a book of theory that is complete in every detail and very subtly written, making its ideas hard to express. More importantly the work requires study and use in order to understand the nuances of its meaning. The 'Annals of the Warring States Period' is a well-written rhetorical compendium the words and actions of the strategists of the School of Diplomacy who were all resourceful, intelligent, aware of the actual situation and gifted in the use of language.