involved, and most of the National Guard had been federalized and concentrated on the border before the end of the affair. Normal relations with Mexico were restored eventually by diplomatic negotiation, and the troops were withdrawn from Mexico in February 1917. Germany was a rival of the U.S. for influence in Mexico. As World War I raged in Europe, Germany was concerned that the U.S. would enter on the side of the British and French. Germany sought to tie down U.S. troops by fomenting war between the U.S. and Mexico. Germany sent a telegram in code outlining a plan to aid Mexico in such a conflict and Mexico's reward would be to regain land lost to the U.S. in the Mexican American War (1846–48). The Zimmermann Telegram was intercepted and decoded by the British and given to Wilson, who then made public. Carranza, whose faction had benefited from U.S. support and then diplomatic recognition, was not drawn into the conflict. Mexico was neutral during World War I, which was a means for Mexico to carve out a role independent of the U.S. as well as the European powers. The Constitutionalists who had won power in 1915-16 drafted a new constitution, adopted in February 1917. For foreign business interests the constitution was alarming, since it empowered the Mexican government to expropriate property deemed in the national interest and asserted rights to subsoil resources, which foreign petroleum companies saw as a direct threat to their interests. More radical elements of the revolution succeeded in having these provisions included, but Carranza did not implement them. U.S. business interests sought the support of the U.S. government against this threat to their enterprises, but Wilson did not act on their behalf. 1918–1919 Minor clashes with Mexican irregulars, as well as Mexican Federales, continued to disturb the U.S.-Mexican border from 1917 to 1919. Although the Zimmermann Telegram affair of January 1917 did not lead to a direct U.S. intervention, it took place against the backdrop of the Constitutional Convention and exacerbated tensions between the USA and Mexico. Military engagements took place near Buenavista, Sonora, on 1 December 1917; in San Bernardino Canyon, Chihuahua, on 26 December 1917; near La Grulla, Texas, on 9 January 1918; at Pilares, Mexico, about 28 March 1918; at the town of Nogales on the Sonora–Arizona border on 27 August 1918; and near El Paso, Texas, on 16 June 1919. Foreign mercenaries