Second, cultural conflict. There have been charges thatnAmericans and Mexicans hated each other, and this led tonwar. In the 141 years since that war, there has been no greatnincrease in love between the two nationalities, but this hasnnot led to another war.nThird, the vacuum theory. This is the belief that “naturenabhors a vacuum.” Thus in 1846, when much of thenSouthwest was thinly populated, Americans rushed in to fillnthe empty space. A cursory glance at population statisticsnfor Mexico in the 1980’s shows that Baja California,nSonora, and Chihuahua still are thinly populated, butnAmericans have not rushed in to claim this land.nFourth, a “slaveocracy conspiracy.” In Congress in then1840’s the question of annexing Texas had been joined withnthe Whig Party’s fight against the institution of slavery andnany extension of it to additional territory. Southerners,naccording to some Whig orators, had conspired to introducensettlers in Texas, settlers who at the proper moment wouldnrevolt against Mexico, then seek annexation to the UnitednStates so that slavery could spread westward. This claim wasnpatently false. No evidence of such a conspiracy survives.nTo justify this theory, a few Whigs proclaimed thatnMexico owned all of Texas, a claim so ludicrous that mostnprominent Whigs contented themselves with asserting thatnMexico owned at least that part of Texas between thenNueces River and the Rio Grande. This claim of thenNueces River as the rightful boundary, incidently, was notnmade by any Mexicans prior to the war. Whigs made it,nbecause they saw it as an issue that might win them the nextnelection, not because they necessarily believed it.nFifth, a desire to annex California. That James K. Polknwanted California cannot be disputed. However, to arguenthat he would have started a war to get it is slanderous. Thenonly war he ever dreamed about was a war on the Whigs.nIn 1846 California already was lost to Mexico. The onlynquestion to be resolved was who would get it: England, thenUnited States, or possibly France. California in the spring ofn1846 had no schools or newspapers, no postal system,nalmost no police or court system, few books, and littlenprotection against Indian raids from the interior. Evenncommunication with Mexico was rare. Many Californiansnopenly expressed their desire for annexation with the UnitednStates, while others favored English sovereignty. To add tonthe confusion there was a virtual civil war raging in thenprovince as Governor Pio Pico contended with Colonel JosenCastro for domination. President Polk was aware of thesencurrents of intrigue and would have been derelict in hisnduty to protect U.S. national interests, had he not tried tonoffset British and French designs in the region. With this innmind, Polk had the Pacific Squadron of the U.S. Navynstanding by, just as he had Captain John Charles Fremontnand a detachment of American soldiers operating in thenarea waiting for the right moment to intervene on behalf ofnAmerican interests.nSixth, the claims question. This concerned the paymentnof debts owed to American citizens by the Mexican government—legitimatendebts somewhat inflated but whichnin that era were considered just cause for war. In 1838nFrance invaded Mexico (the so-called Pastry War) overnclaims owed French citizens. The claims issue had simmerednbetween the United States and Mexico since 1829.nIn 1846 these had not been settled, but they did not causenthe outbreak of fighting.nFinally, it was not the annexation of Texas to the Unionnthat began the war with Mexico, although many historiansnhave argued this. On March 1, 1845, President John Tylernsigned the joint resolution calling for the annexation ofnTexas, and five days later Mexican Ambassador Juan N.nAlmonte demanded his passport and stormed out of thenUnited States, asserting that the annexation of Texasnamounted to a declaration of war. However, his actionsnwere motivated by Mexican internal politics, not by any realnbelief that Texas was still owned by Mexico. Texans hadndeclared independence in 1836, had maintained that independencenfor almost 10 years, and had been recognized asnindependent by the United States, England, France, andnseveral other nations. Even Mexico in the summer of 1845noffered to formally recognize Texas independence, providednTexans would not join the Union. Then what did cause thenwar between the United States and Mexico?nAfter Mexico won its independence from Spain, twonpolitical parties emerged: the Centralists and the Federalists.nThe Centralists favored a strong central government, whilenthe Federalists wanted a government patterned after thenUnited States. In 1822-1823 the Centrahsts were in power.nThen the Federalists assumed control and wrote the Constitutionnof 1824 establishing a federal republic.nStable constitutional government lasted only until 1829nwhen there began a series of revolutions which culminatednin 1835 when Antonio Lopez de Santa Anna overthrew thenconstitution and set himself up as dictator (which, incidentally,nled to rebellion in seven Mexican states, includingnTexas). Chaos followed with coup and countercoup, revolutionnand counterrevolution. In 1845, when Texas soughtnannexation to the United States, the Federalists had justnregained power. Ambassador Almonte was the representativenof a Centralist regime and expected to be ordered homenmomentarily. His protest at the annexation of Texas,ntherefore, was intended more to embarrass the Federalistsnand solidify popular support for the Centralists than tonrepresent any genuine Mexican claim to Texas.nDuring the remainder of the year 1845, the Centralistsnused the issue of the annexation of Texas to work a majoritynof Mexicans into a war fever. President Polk that year triednevery honorable means to avoid war. Early in his administrationnhe inquired if the Federalist government in Mexiconwould receive a minister empowered to negotiate all pointsnof difference between the two nations. Assured that such annambassador would be received, Polk dispatched John Slidellnwith an offer to purchase New Mexico and California.nHowever, by the time Slidell arrived in Mexico, thenCentralists had created such a climate of hatred that nongovernment there could even talk with the United States.nSlidell left Mexico without being able to discuss the issues.nThen early in 1846 came yet another revolution in Mexiconwith the Centralists returning to power under the leadershipnof Mariano Paredes.nWar broke out in 1846, primarily because MarianonParedes and his advisors believed that such a war would benwon by Mexico. They thought they could count on Britishnaid in the event of war (a belief the British encouraged, fornin 1845-46 they were negotiating the boundary betweennnnAUGUST 1987 /13n