Every government begins with a successful act of treason against the prior government. Most government reforms begin with an act that if not successful would be deemed treason.

* Sulla who became dictator of Rome
* Caesar who cross the Rubicon
* The American Constitutional convention, summoned to reform the articles of Confederation but instead created a new government that violated the core principles of the old government and was submitted to the people for approval (explicitly ignoring/discounting votes by the existing government)
* Thomas Jefferson who purchased Louisiana in an act that he admitted was extra-legal
* Abraham Lincoln transformed American government; the country that elected him was not the country that existed at the time of his death. 
* Napoleon (and thousands of other Frenchman) - who betrayed the country he had sworn to serve, then betrayed the committee on state security that he had sworn to serve, then betrayed the directorate he had sworn to serve, then betrayed the exile he had sworn to serve.  You can list probably 10,000 other Frenchman in this category
* [Toussaint Louverture][1]
* [Current leaders who came to power through a Coup d'etat][2]
* [Iranian Coup][3]

There are limitless additional examples. 


  [1]: https://en.wikipedia.org/wiki/Toussaint_Louverture
  [2]: https://en.wikipedia.org/wiki/Coup_d%27%C3%A9tat#Current_leaders_who_assumed_power_via_coups_d.27.C3.A9tat
  [3]: https://history.stackexchange.com/q/26495/1401