Final answer:
O'Sullivan is calling on Americans to support and participate in the nation's territorial expansion, an idea known as 'Manifest Destiny.' His rhetoric supported the overarching economic and political goals of a U.S. government committed to expansion during his time.
Step-by-step explanation:
O'Sullivan is famously associated with the concept of "Manifest Destiny," a phrase which encapsulated the belief that the expansion of the United States across the North American continent was both justified and inevitable. While not explicitly mentioned in the information provided, O'Sullivan's call to Americans, in the context of his writings, would be to support and participate in the nation's territorial expansion.
This idea is supported by the evidence that his words aligned with the economic and political goals of a federal government committed to expansion, suggesting O'Sullivan was rallying the public to the cause of national growth.
In the context of other provided statements, which seem to relate broadly to governmental responsibilities, civic participation, and the role of individuals in a democratic society, O'Sullivan's call involved participating in American democracy.
The references to concrete proposals such as voting reform, the Oath of Allegiance, and the construction of a "Great Society" reflect a broader theme of civic action and the shaping of American society in alignment with constitutional principles and democratic values.