Final answer:
The claim by Leon Panetta in 2011 about the New Dawn military campaign's conclusion in Iraq is not provided, but the context reflects the premature declaration of "Mission Accomplished" and the ensuing prolonged occupation and instability.
Step-by-step explanation:
The main claim from Leon Panetta in 2011 concerning the end of the New Dawn military campaign in Iraq was not explicitly mentioned in the given information. However, the context provided reveals that initial expectations of the American and Iraqi people for a swift transition to democracy and stability after the fall of Saddam Hussein proved to be overly optimistic.
President George Bush's assertion on May 1, 2003, that "major combat operations in Iraq have ended" was followed by a period marked by insurgency, civilian casualties, and sectarian strife. This indicates that the New Dawn military campaign’s conclusion was complicated and did not bring the anticipated peace and prosperity. Instead, it led to an extended occupation by US forces, who faced challenges in stabilizing Iraq and transitioning it towards self-governance amid growing violence and political uncertainty.