For students of the poet, Robert Fallon's Milton in Government fills a gap in modern knowledge of his life, the ten years he labored as Secretary for Foreign Languages to the English Republic. For Interregnum historians, the book offers a study of the international affairs of the Republic from a unique perspective, as well as a detailed analysis of the government bureaucracy that conceived and articulated foreign policy during the 1650s. Milton's decade of public service to the English Republic, and the collection of State Papers which are the product of those years, have been either misunderstood or largely ignored by Miltonists, and their influence upon his poetry all but dismissed.

Making extensive use of the State Papers Foreign in the Public Record Office, hitherto overlooked by literary scholars, and the Calendar of State Papers Domestic, Fallon offers the first definitive description of the poet's place in government. He finds Milton to be an indefatigable and highly knowledgeable public servant, closely involved in the expression of foreign policy, and responsible for many more documents than have been previously ascribed to him. His State Letters reveal him as a man intimately aware of international events, a consideration which leaves little doubt that his experience in government had a significant influence on his creative imagination.

Fallon also provides a reading of Milton's tracts of 1659–1660, tracing the influence of a decade of public service in his political philosophy and questioning historians' conclusions that he was repudiating Cromwell's Protectorate in his appeal to stave off the Restoration.