According to the convention of Zhou dynasty, a large fiefdom was allowed to have as many as three armies. Since Jin was a large fiefdom, it was permitted by the Zhou king to own three armies. However, Jin originally had only one army: the limitation was imposed by the Zhou dynasty king in order to observe the rite of Zhou. In 679 BCE, Duke Wu of Quwo assassinated Marquis Xiaozi of Jin and became the ruler of Jin. Quwo was a cadet branch of Jin's ruling house; Ji clan descended from Shu Yu of Tang. The Zhou court, which regarded the lineal legitimacy as an extremely important matter, could not agree with such an usurpation. As a consequence, the king revoked Jin's permission to have three armies.