The Military Revolution is the theory that a series of radical changes in military strategy and tactics during the 16th and 17th centuries resulted in major lasting changes in governments and society. The theory was introduced by Michael Roberts in the 1950s as he focused on Sweden (1560–1660) searching for major changes in the European way of war caused by the introduction of portable firearms. Roberts linked military technology with larger historical consequences, arguing that innovations in tactics, drill and doctrine by the Dutch and Swedes (1560–1660), which maximized the utility of firearms, led to a need for more trained troops and thus for permanent forces (standing armies). Armies grew much larger and more expensive. These changes in turn had major political consequences in the level of administrative support and the supply of money, men and provisions, producing new financial demands and the creation of new governmental institutions. "Thus, argued Roberts, the modern art of war made possible—and necessary—the creation of the modern state". In the 1990s the concept was modified and extended by Geoffrey Parker, who argued that developments in fortification and siege warfare caused the revolution. Parker also argues that the military revolution in Europe gave European powers a distinct advantage, making it possible for the relatively small European powers to conquer the Americas, as well as large parts of Africa and Asia. Parker's argument has been criticized by Cambridge University political scientist Jason Sharman. The concept of a military revolution during this time has received a mixed reception among historians. Noted military historians Michael Duffy and Jeremy Black strongly criticized the theory and have described it as misleading, exaggerated, and simplistic. Origin of the concept Roberts first proposed the concept of a military revolution in 1955. On 21 January of that year he delivered a lecture before the Queen's University of Belfast; later published as an article, "The Military Revolution, 1560–1660," that has fueled debate in historical circles for five decades, in which the concept has been continually redefined and challenged. Though historians often challenge Roberts' theory, they usually agree with his basic proposal that European methods of warfare changed profoundly somewhere around or during the Early Modern Period. Chronology Roberts placed his military revolution around 1560–1660 as the period in which linear tactics were developed to take advantage of the increasingly effective gunpowder weapons; however, that chronology has been challenged by many scholars. Ayton and Price