The August of 1866 saw two diplomatic developments for the United States. First, another major war in Europe started with Russia and Montenegro declaring war on Austria and a half dozen German minors. The second was the end of the Mexican Peace Treaty. Though tempted, David realized that the country still needed time to adjust to the new President, as well as, the country needed time to finish expanding factories and infrastructures. However, David still ordered an increase in defense spending and an increase in the strength of the divisions along the Mexican border. So, that by November of 1866, sufficient forces were in place to attack Mexico. War was declared on November 1st and the four armies arrived in Villa do Leon, Tampico, San Juan del Rio and Colima roughly three weeks later. The American forces liberated those four provinces before moving on to Valladolid, Veracruz, Tlascala and Tejupa. So that by the second week of January 1867, the American forces had liberated eight Mexican provinces without firing a single shot in combat. The next to fall was the capital of Mexico City and a quick offer of peace with the United States receiving: Veracruz, Tejupa, Valladolid, Tlascala, Loreto, Tampico, Colima, San Juan del Rio and Villa de Leon.
Even with the quick victory of Mexico, the American public was turning against the President. David also realized that even though he had spent the time ‘in between’ war working on infrastructure and industry, the country was needed a massive overhaul. Therefore, David ordered drastic cutbacks in the Military and spent the next four years expanding resource collections, factories and railroads. Even though America remained at peace during the late 1860s, the Austrio-Russian War continued until 1868 when Austria surrenders Brody, Lviv, Przemysl, Ternopol and Dubrovnik to Russia. Late 1870 saw French colonial ambitions fuel a war with Morocco and the Ottoman Empire, with the Spanish, Sicilians and Egyptians quickly joining France in hopes of gaining their own small piece of the pie.
David now acting as President Grant started to receive reports in late 1870 of transfers of Spanish garrisons from the Philippines to Ottoman Front. David quickly ordered the transfer of two South American Command divisions to the Pacific command and the creation of two replacement divisions for the South American Command. The Pacific fleet shuttled the forces from the West Coast to the South Pacific in preparation for the Spanish-American War. During the first half of 1871 forces in the Greek, Pacific and African Commands were reinforced and brought up to full strength, so that on July 4th 1871, twin declarations of war were issued to Oman and Spain. The American forces struck quickly before the Spanish could react. The Pacific command landed forces on Mindoro and Mindanao, while the Atlantic fleet landed six divisions from the Greek Command in Sevilla within two weeks of the declaration of war. Sevilla was liberated on August 6th, but the Spanish had regrouped and counter attack that same day. After a fierce two day battle, the Spanish were driving off with the American in hot pursuit. Leaving behind one engineering division to secure the beachhead, the rest of the American force moved inland toward Cordoba, where the American caught up to the retreating Spanish and routed them on August 27th. Meanwhile, the East African command moved against the Oman capital, captured and annex the county without difficulty. However, the Western African command quickly realized that it did not have sufficient forces to dislodge the Spanish garrisons, so instead the Americans simply dug in near the Spanish forces to ‘keep them pinned down’, while the African cavalry moved around western Africa securing Spanish trading posts. By mid September, Cordoba was liberated, but Spain was counter attacking both Cordoba and Sevilla from all directions. Luckily the counter-attacks were not coordinated and were defeated piecemeal. Again, the Americans left one division in Cordoba and moved the remainder of the army northeast to the next province. By the end of September, the Spanish counter attacks began to lessen and the Americans continued their slow advance toward Madrid. Also, by the end of September, the Pacific command had liberated Mindoro and Mindanao, and had successfully landed troops Luzon. The Pacific commander had chosen Luzon because it was the only undefended province on the Philippine mainland. Throughout the fall of 1871, the Americans continued their advance toward Madrid they noticed two things. First, that one in three divisions that they faced appeared to be French divisions that were loaned to Spain and second, that a majority of counter attacks were coming from north of the American forces and west of Madrid. So, a plan was developed that once Madrid fell, the American army would turn west and loop back around to cut off and annihilate the Spanish/French forces. On November 13th 1871, American forces liberated Madrid. On November 14th, Spain sued for peace with the Ottoman Empire with a return to status quo. That same day, American forces, less one garrison division for Madrid, set off toward Toledo Spain. Although the American forces were able to reach Toledo and liberate the province, they were not able to advance any futher. Spanish forces continuously counter attacked and counter attacked. Though the Americans were never in danger of losses any divisions and won the battles easily, they realized that they could simply dig in and wait for the Spanish to give up. During this same time the Pacific command liberated Luzon and started to prepare a trap in anticipation of a Spanish attack and although the Spanish did not counter attack Luzon, they did shift there troops out of Leyte into Manilla, thus allowing the Americans to land troops into an undefended Leyte. Then once Leyte was liberated, pincer attack from Luzon and Leyte attacked Manilla and destroyed the Spanish’s Philippine army in early 1872. The American forces were extended as far as they could safely go without risking the loss of the forces, so negotiations started with the Spanish over terms. So on February 6, 1872, Spain surrendered all of their Philippine colonies, African colonies and Puerto Rico to the United States. When David read the treaty, he slapped his forehead and said, “Puerto Rico! I forgot about Puerto Rico, good thing they offered that colony or we would have had another war in five years.”
A few days later, David split off two divisions from the African command and named them the Arabian Command and ordered them to cross the border and annex Abu Dhabi, so that by June of 1872, Abu Dhabi was part of the United States.