鲁定公九年（前501年）阳货被逐，孔子才见用于鲁，被任为中都宰，是年孔子五十一岁。“行之一年，四方则之”。遂由中都宰迁司空，再升为大司寇。鲁定公十年（前500年）齐鲁夹谷之会，鲁由孔子相礼。孔子认为“有文事者必有武备，有武事者必有文备”，早有防范，使齐君想用武力劫持鲁君之预谋未能得逞，并运用外交手段收回被齐侵占的郓、灌、龟阴之田。定公十二年（前498年）孔子为加强公室，抑制三桓，援引古制“家不藏甲，邑无百雉之城”提出“堕三都”的计划，并通过任季氏宰的子路去实施。由于孔子利用了三桓与其家臣的矛盾，季孙氏、叔孙氏同意各自毁掉了费邑与后邑。但孟孙氏被家臣公敛处父所煽动而反对堕成邑。定公围之不克。孔子计划受挫。

In the 9th year of the era of Lord Ding, Duke of Lo (鲁定公), Yang Foh was disposed. At the age of 51, Confucius was commissioned as the Officer-in-charge of Jung Doh (中都宰).  ‘By one year under his governing, Jung Doh was the model city of the area’.  He was promoted as Director of Engineering (司空) and then as Minister of Justice (大司寇).  During the 10th year of the era of Lord Ding, i.e. 500BC, Chaai and Lo states had a summit meeting in Hap Guk (夹谷, name of a place), and Confucius served as the Master of Ceremony.  His concept was that ‘ even in a civil function it must be backed by the military force; in a military action it must have a civil support’, so he prepared for the unexpected.  By this vision, the Duke of Chaai could not exercise his hostage plan to the Duke of Lo.  By his diplomatic skill, Confucius regained the lands in Gwan, Goon and Gwai Yam (郓, 灌, 龟阴name of places) that were once captured by the Chaai state.  In the 12th year of the Lord Ding era, i.e. 498 BC, trying to suppress the power of the Three Woon families and to restore the power of the Duke, Confucius quoted the old doctrine that ‘ no military force in a dignitary family and no township should have a city wall over thirty thousand feet long’.  He suggested eliminating the power of the three capital-like towns.  He pushed his plan by Ji Lo, his student and the Officer-in-charge in the Gwai Si Family.  Utilizing the conflicts between the Three Woon families and their family subordinate officers, Confucius made the Gwai Sun Si (季孙氏) and Suk Sun Si (叔孙氏) to agree to destroy the power of Fai Township and the Hau Township (费邑与后邑). Yet the Meng Sun Si  (孟孙氏), as convinced by his family subordinate officer Gong-gim Chu Fu (公敛处父), objected the elimination of the Sing Township (成邑).  Even after surrounded the Sing Township, Lord Ding was not able to conquer on his invasion and the plan was obstructed.