The appointment of Oliver Cromwell as Lord Protector occurred in a period of great political upheaval following the English Civil War. This pivotal moment followed the execution of King Charles I, which had led to the establishment of the Commonwealth of England. Cromwell, a key military leader and member of the Parliamentarian faction, emerged as the dominant figure in this new political landscape. His rise to power was characterized by a blend of military might and moral authority, reflecting his firm belief in a government based on Puritanic principles. The title of Lord Protector conferred upon Cromwell was unique, combining powers typically divided between the monarchy and Parliament.

Cromwell's formal installation took place in Westminster, where he took an oath to uphold the laws of the Commonwealth and promote a godly government. His leadership focused on reforming governance, including efforts to centralize authority and maintain order in the wake of the civil strife. With this new position, he sought to establish a stable government that emphasized religious tolerance, albeit selectively favoring Protestant sects. Cromwell's Protectorate would continue to navigate through various confrontations, internally and externally, as he aimed to solidify the Commonwealth's legitimacy.

Cromwell's rule as Lord Protector lasted until his death in 1658, during which he faced significant challenges, including political dissent, economic hardship, and international conflict. His administration engaged in military campaigns, notably the conquest of Ireland and Scotland, which were aimed at integrating these regions into the Commonwealth under his leadership. His legacy remains controversial, as opinions about his governance range from views of him as a stabilizing force to criticisms of tyrannical rule, impacting English political thought for generations to come.