The Mexican-American War in the mid 19th century expanded the territory of the United States and fulfilled the manifest destiny Americans believed was the United States should stretch from ocean to ocean. The results of this war had a dramatic impact on the nation in that it placed the issue of the expansion of slavery into the forefront of politics of the 1850s. This conflict over slavery in the newly acquired territories and existing unsettled territories catapulted the nation into a civil war.
Document 1 shows how President Polk justified the war with Mexico. President Polk went before Congress to ask for a declaration of war against Mexico. The President argued that American blood was shed on American soil and the only course of action left after many attempts to resolve the issue was war. Document 2 shows how many Americans believed in American expansion. John O’Sullivan coined the phrase “manifest destiny” in an article in the Democratic Review in 1839. Many Americans believed that the nation’s founding and history was proof that Americans were a special people chosen by God to fulfill freedom and civilization across the continent. Document 3 shows how the annexation of Texas was a controversial issue that divided the nation. Some Americans felt that the annexation of Texas was unjust and unlawful. One reason was that Mexico still felt that Texas was part of Mexico and others did not want it added as a slave state. Many Americans however, such as O’Sullivan justified annexation and explained why it was the right course of action. Document 4 shows that many people in Mexico were outraged by what they considered an invasion from a foreign power to the North. In this article, the author states why Mexico had no choose to fight the war with the United States. Document 5 shows how Lincoln challenged President Polk’s justification for war with Mexico. These resolutions presented by first term Congressman Abraham Lincoln requested President James K. Polk to provide Congress with the exact location (the "spot") upon which blood was spilt on American soil, as Polk had claimed in 1846 when asking Congress to declare war on Mexico. : Lincoln had serious questions on whether the war with Mexico was justified or instigated by the U.S. government for the sole purpose of acquiring lands from Mexico Lincoln's resolutions were a direct challenge to the validity of the president's words, and representative of an ongoing political power struggle between Whigs and Democrats. Document 6 shows how Charles Sumner an Abolitionist and crusader for peace believed the war with Mexico was fought to expand slavery in America and the power of the slave states. This speech was adopted by the Massachusetts legislature in 1847. Procedure (80 minutes):
Introduction of lesson, objectives, overview of SAC procedure (15 minutes)
SAC group assignments (30 minutes)
Assign groups of four and assign arguments to each team of two.
In each group, teams read and examine the Document Packet
Each student completes the Preparation part of the Capture Sheet (#2), and works with their partner to prepare their argument using supporting evidence.
Students should summarize your argument in #3.
Position Presentation (10 minutes)
Team 1 presents their position using supporting evidence recorded and summarized on the Preparation part of the Capture Sheet (#2 & #3) on the Preparation matrix. Team 2 records Team 1’s argument in #4.
Team 2 restates Team 1’s position to their satisfaction.
Team 2 asks clarifying questions and records Team 1’s answers.
Team 2 presents their position using supporting evidence recorded and summarized on the Preparation part of the Capture Sheet (#2 & #3) on the Preparation matrix. Team 1 records Team 2’s argument in #4.
Team 1 restates Team 2’s position to their satisfaction.
Team 1 asks clarifying questions and records Team 2’s answers.
Consensus Building (10 minutes)
Team 1 and 2 put their roles aside.
Teams discuss ideas that have been presented, and figure out where they can agree or where they have differences about the historical question
Closing the lesson (15 minutes)
Make connection to unit
Assessment (suggested writing activity addressing the question)
DOCUMENT PACKET Document 1
(In an earlier message) I informed you that… I had ordered an efficient military force to take a position "between the Nueces and Del Norte." This had become necessary to meet a threatened invasion of Texas by the Mexican forces…. The invasion was threatened solely because Texas had determined, in accordance with a solemn resolution of the Congress of the United States, to annex herself to our Union, and under these circumstances it was plainly our duty to extend our protection over her citizens and soil…
The Congress of Texas, by its act of December 19, 1836, had declared the Rio del Norte to be the boundary of that Republic. …The country between that river and the Del Norte …is now included within one of our Congressional districts…It became, therefore, of urgent necessity to provide for the defense of that portion of our country…(On the 24th of April) a party …of sixty-three men and officers, were…dispatched from the American camp up the Rio del Norte, on its (North) bank, to ascertain whether the Mexican troops had crossed, or were preparing to cross, the river…(They) became engaged with a large body of these (Mexican) troops, and , after a short affair, in which some sixteen (Americans) were killed and wounded, appear to have been surrounded and compelled to surrender…
We have tried every effort at reconciliation. The cup of forbearance had been exhausted even before the recent information from the frontier of the Del Norte. But now,…Mexico has passed the boundary of the united States, has invaded our territory and shed American blood upon American soil.
annex: take possession of
forbearance: patience, tolerance or self-control
accordance: agreement to a course of action
Source: "PBS The West." James K. Polk Message on War with Mexico May 11, 1846. N.p., n.d. Web. 30 May 2012. .
The far-reaching, the boundless future will be the era of American greatness. In its magnificent domain of space and time, the nation of many nations is destined to manifest to mankind the excellence of divine principles; to establish on earth the noblest temple ever dedicated to the worship of the Most High -- the Sacred and the True. Its floor shall be a hemisphere -- its roof the firmament of the star-studded heavens, and its congregation an Union of many Republics, comprising hundreds of happy millions, calling, owning no man master, but governed by God's natural and moral law of equality, the law of brotherhood -- of "peace and good will amongst men.". . .
…We must onward to the fulfilment of our mission -- to the entire development of the principle of our organization -- freedom of conscience, freedom of person, freedom of trade and business pursuits, universality of freedom and equality. This is our high destiny, and in nature's eternal, inevitable decree of cause and effect we must accomplish it. All this will be our future history, to establish on earth the moral dignity and salvation of man -- the immutable truth and beneficence of God. ..Who, then, can doubt that our country is destined to be the great nation of futurity?
Source: "The Great Nation of Futurity," The United States Democratic Review, Volume 6, Issue 23, pp. 426-430. The complete article can be found in The Making of America Series at Cornell University
 It is time now for opposition to the Annexation of Texas to cease . . . . It is time for the common duty of Patriotism to the Country to succeed;—or if this claim will not be recognized, it is at least time for common sense to acquiesce with decent grace in the inevitable an irrevocable.
 It is wholly untrue, and unjust to ourselves, the pretence that the Annexation has been a measure of spoliation, unrightful and unrighteous—of military conquest under forms of peace and law—of territorial aggrandizement at the expense of justice due by a double sanctity to the weak.
. . . The independence of Texas was complete and absolute. It was an independence, not only in fact but of right. . . .
aggrandizement: to increase the size or scope of something
Source: John L. O’Sullivan, “Annexation,” The United States Magazine and Democratic Review, Vol. XVII, 1845
The conflict which we are engaged with the United States of the North cannot be worthily maintained unless the whole nation is profoundly convinced that its interest imperatively require that it should be prosecuted with insuperable energy-not to be shaken by a reverse, nor satisfied with a partial victory. Such is the true point of view of the question at this moment.
In the civilized world war is not the result of savage impulses of hatred and revenge; it is only a measure of national defense-destructive, to be sure, but legitimate. Nations do not wage war save to preserve and secure their rights; and hence it follows that when they have justice on their side, they should never lay down their arms until they have obtained these important ends. In our case, Mexico is defending the interests of her nationality, her territory, and her race; resisting the invasions with which the people of the United States threaten to occupy our country, to incorporate us with the American Union, and to extend themselves across the continent. We therefore must regard, as our object in the war, the preservation of our territory and the establishment of relations which shall assure its future security.
insuperable: impossible to overcome
legitimate: rightful or justifiable
assure: to make something certain to happen
Source: "The Foreign War." El Republicano [Mexico City] 03 04 1847, n. pag. Web. 26 May. 2012.
Lincoln Spot resolution
And yet again, in his message of December 7, 1847, that "the Mexican Government refused even to hear the terms of adjustment which he [our minister of peace] was authorized to propose, and finally, under wholly unjustifiable pretexts, involved the two countries in war, by invading the territory of the State of Texas, striking the first blow, and shedding the blood of our citizens on our own soil."
And whereas this House is desirous to obtain a full knowledge of all the facts which go to establish whether the particular spot on which the blood of our citizens was so shed was or was not at that time our own soil: Therefore,
Resolved By the House of Representatives, That the President of the United States be respectfully requested to inform this House --
1st. Whether the spot on which the blood of our citizens was shed, as in his messages declared, was or was not within the territory of Spain, at least after the treaty of 1819, until the Mexican revolution.
2d. Whether that spot is or is not within the territory which was wrested from Spain by the revolutionary Government of Mexico.
3d. Whether that spot is or is not within a settlement of people, which settlement has existed ever since long before the Texas revolution, and until its inhabitants fled before the approach of the United States army.
4th. Whether that settlement is or is not isolated from any and all other settlements by the Gulf and the Rio Grande on the south and west, and by wide uninhabited regions on the north and east.
5th. Whether the people of that settlement, or a majority of them, or any of them, have ever submitted themselves to the government or laws of Texas or the United States, by consent or compulsion, either by accepting office, or voting at elections, or paying tax, or serving on juries, or having process served upon them, or in any other way.
6th. Whether the people of that settlement did or did not flee from the approach of the United States army, leaving unprotected their homes and their growing crops, before the blood was shed, as in the messages stated; and whether the first blood, so shed, was or was not shed within the enclosure of one of the people who had thus fled from it.
7th. Whether our citizens, whose blood was shed, as in his message declared, were or were not, at that time, armed officers and soldiers, sent into that settlement by the military order of the President, through the Secretary of War.
8th. Whether the military force of the United States was or was not sent into that settlement after General Taylor had more than once intimated to the War Department that, in his opinion, no such movement was necessary to the defense or protection of Texas.
pretexts: a misleading or untrue reason given for doing something in an attempt to conceal the real reason
Source: "Abraham Lincoln: Spot Resolutions." America's Civil War. N.p., n.d. Web. 30 May 2012. .
Mexico, on achieving her independence of the Spanish Crown…decreed the abolition of human slavery within her dominions, embracing the province Texas…
At this period, citizens of the United States had already begun to (move) into Texas…The idea was …that his extensive province ought to become a part of the United States…
A current emigration soon followed from the United States. Slaveholders crossed the Sabine (rive between Louisiana and Texas) with their slaves, in defiance of the Mexican ordinance of freedom. Restless spirits, discontented at home…joined them…The work of rebellion sped. Our newspapers excited the lust of territorial robbery in the public mind…Certainly (Mexico)…might justly charge our citizens denied) the great truths of American freedom…
dominions: ruling power, authority, or control
emigration: to leave a place to live somewhere else
Source:Charles Sumner, “Objections to the Mexican-American War,” adopted by the Massachusetts State Legislature, 1847.
Don’t forget the rules of a successful academic controversy!
Practice active listening.
Challenge ideas, not each other
Try your best to understand the other positions
Share the floor: each person in a pair MUST have an opportunity to speak
No disagreeing until consensus-building as a group of four
Was the Mexican War justified?
Highlight your assigned position.
Yes: The Mexican War was justified.
No: The Mexican War was not justified.
Read through each document searching for support for your side’s argument. Use the documents to fill in the chart (Hint: Not all documents support your side, find those that do):
What is the main idea of this document?
What details support your position?
Work with your partner to summarize your arguments for your position using the supporting documents you found above:
You and your partner will present your position to your opposing group members. When you are done, you will then listen to your opponents’ position.
While you are listening to your opponents’ presentation, write down the main details that they present here:
Clarifying questions I have for the opposing partners:
How they answered the questions:
Put your assigned roles aside. Where does your group stand on the question? Where does your group agree? Where does your group disagree? Your consensus answer does not have to be strictly yes, or no.