The reign of Alfonso XIII is the period of Spanish history in which Alfonso XIII of Bourbon reigned. From the moment of his birth in May 1886 he was king, as his father Alfonso XII had died five months earlier. During his childhood, his mother María Cristina de Habsburgo-Lorena was head of state as regent until May 1902, when he turned sixteen and took the oath of office under the Constitution of 1876, when he began his personal reign, which lasted until 14 April 1931, when he had to go into exile after the proclamation of the Second Republic. The reign is usually divided into several stages: The regency of Maria Cristina of Habsburg (1885-1902) was "a particularly significant period in the history of Spain, for in those years at the end of the century the system knew its stabilisation, the development of liberal policies, but also the appearance of major fissures that in the international arena were expressed first with the colonial war and later with the US, causing the military and diplomatic defeat that led to the loss of the colonies after the Treaty of Paris in 1898. On the domestic front, Spanish society underwent a considerable mutation, with the emergence of such significant political realities as the emergence of n, the strengthening of a workers' movement with dual socialist and anarchist affiliation, and the continued persistence, albeit declining, of the Republican and Carlist oppositions. The constitutional period (1902-1923) was the period of his personal reign during which King Alfonso XIII kept to the role conferred on him by the 1876 Constitution which governed during the Bourbon Restoration in Spain, although he did not limit himself to playing a symbolic role but actively intervened in political life, especially in military matters, thanks to the relatively broad powers held by the Crown. The political king, the politician on the throne, was thus an obstacle to the transformation of the political regime of the Restoration into a parliamentary monarchy, and his intervention "became more marked at times when the parties (of the time) showed little internal cohesion and opinion did not opt for a leader in a clear way.