with the Spanish Captaincy General of Venezuela. Although Spain still claimed the region, the Spanish did not contest the treaty because they were preoccupied with their own colonies' struggles for independence war. During the Campaign of Guayana, in 1817 General Manuel Piar fought against the royalists to seize the missions of Spanish Guyana. After releasing Tumeremo, the Spanish survivors were imprisoned and sentenced to death. From there, the city was a strategic site and barracks for the patriot soldiers commanded by Simón Bolívar. From 1830 many indigenous and other populations began to emerge around Tumeremo. On 21 July 1831, Demerara-Essequibo was united with Berbice to create British Guiana with the Essequibo River as its west border, although many British settlers lived west of the Essequibo. In 1894, a group of British settlers who came from the British Guyana tried to establish themselves near Tumeremo in what is now Sifontes Municipality. General Domingo Antonio Sifontes claimed the area on 2 March 1894 near El Dorado, where Venezuela established a military position. After expelling the settlers from the area, Sifontes became a local hero in recognition of his defense of Venezuelan sovereignty. Venezuela had in the course of the dispute repeatedly appealed to the US and to the Monroe Doctrine, but the US government had declined to involve itself. That changed after Venezuela obtained the services of William Lindsay Scruggs. Scruggs, a former US ambassador to Colombia and Venezuela, was recruited in 1893 by the Venezuelan government to operate on its behalf in Washington D.C. as a lobbyist and legal attache. Scruggs had apparently resigned his ambassadorship to Venezuela in December 1892 but had been dismissed by the US for bribing the President of Venezuela. As a lobbyist, Scruggs published an October 1894 pamphlet, British Aggressions in Venezuela:, or the Monroe Doctrine on Trial in which he attacked "British aggression" and claimed that Venezuela was anxious to arbitrate over the Venezuela-British Guiana border dispute. Scruggs also claimed that British policies in the disputed territory violated the Monroe Doctrine of 1823. For much of the 19th century, it had only rarely been invoked by the United States, but a "paradigm shift in U.S. foreign relations in the late nineteenth century" saw Americans more actively support their increasingly-significant economic interests in Central and South America. The "'new diplomacy' thrust the United States more emphatically into the imperial struggle". It was in that context that