Answer to Question #89759 in Other History for niah
Polk wanted to push Mexico into negotiating with the United States, and he was willing to create a threat of war to do this. If he had to fight, he wanted a short war and a quick victory. He never expected a long-drawn-out war. The Army was not ready for war and had never fought so far from home before. The country was divided. So Polk was taking a considerable risk in his bold stand toward Mexico.
Negotiations might have been possible if Polk had tried a different approach. Mexico had refused to recognize either the independence of Texas or its annexation by the United States, and when annexation occurred, broke relations and withdrew its minster from Washington.
Americans were reaching out beyond their border. Advancements in transportation and communications technologies were dissolving the nation's geographic and cultural isolation. Commerce expanded and travel increased as interest in exploration carried Americans around the globe. The war was a "window" through which Americans saw a strange and exotic land of alien manners, customs, and attitudes. Many were convinced that America would never be the same.