On May 9, James K. Polk stated in his regular semi-weekly meeting with his cabinet that in view of Slidell's rejection by the Mexican government, the United States now had "ample cause of war." Polk favored sending Congress a message recommending a declaration of war, a decision endorsed by all members of the cabinet except secretary of the navy, George Bancroft, who remarked he would feel "better satisfied" if Mexican forces had committed an act of aggression. The cabinet adjourned, having agreed to submit a war message to Congress. A few hours later, however, Polk received word that Mexican troops had attacked two companies of dragoons on the Rio Grande. Polk immediately summoned the cabinet, which unanimously endorsed the decision to ask for a declaration of war.
SATURDAY, 9th May, 1846.--The Cabinet held a regular meeting today; all the members present. I brought up the Mexican question, and the question of what was the duty of the administration in the present state of our relations with that country. The subject was very fully discussed. All agreed that if the Mexican forces at Matamoras committed any act of hostility on Gen'! Taylor's forces I should immediately send a message to Congress recommending an immediate declaration of War. I stated to the Cabinet that up to this time, as they knew, we had heard of no open act of aggression by the Mexican army, but that the danger was imminent that such acts would be committed. I said that in my opinion we had ample cause of war, and that it was impossible that we could stand in statu quo, or that I could remain silent much longer; that I thought it was my duty to send a message to Congress very soon & recommend definitive measures. I told them that I thought I ought to make such a message by tuesday next, that the country was excited and impatient on the subject, and if I failed to do so I would not be doing my duty. I then propounded the distinct question to the Cabinet and took their opinions individually, whether I should make a message to Congress on tuesday, and whether in that message I should recommend a declaration of War against Mexico. All except the Secretary of the Navy gave their advice in the affirmative. Mr. Bancroft dissented but said if any act of hostility should be committed by the Mexican forces he was then in favour of immediate war. Mr. Buchanan said he would feel better satisfied in his course if the Mexican forces had or should commit any act of hostility, but that as matters stood we had ample cause of war against Mexico, & he gave his assent to the measure. It was agreed that the message should be prepared and submitted to the Cabinet in their meeting on tuesday. A history of our causes of complaint against Mexico had been at my request previously drawn up by Mr. Buchanan. I stated that what was said in my annual message in December gave that history as succinctly and satisfactorily as Mr. Buchanan's statement, that in truth it was the same history in both, expressed in different language, and that if I repeated that history in [a] message to Congress now I had better employ the precise language used in my message of December last. Without deciding this point the Cabinet passed to the consideration of some other subjects of minor importance. The Cabinet adjourned about 2 O'Clock P. M. Before they separated I directed the Secretary of State to have all the correspondence of Mr. Slidell with the Mexican Government, & such portions of his correspondence with the Department of State as it was proper to communicate copied; and in like manner I directed the Secretary of War to have all his orders to Gen'l Taylor commanding the army in Texas copied, so as to have these documents ready to be communicated to Congress with my message.
About 6 o'clock P. M. Gen'l R. Jones, the Adjutant General of the army, called and handed to me despatches received from Gen'l Taylor by the Southern mail which had just arrived, giving information that a part of [the] Mexican army had crossed to the Del Norte, [crossed the Del Norte] and attacked and killed and captured two companies of dragoons of Gen'l Taylor's army consisting of 63 officers & men. The despatch also stated that he had on that day (26th April) made a requisition on the Governors of Texas & Louisiana for four Regiments each, to be sent to his relief at the earliest practicable period. Before I had finished reading the despatch, the Secretary of War called. I immediately summoned the Cabinet to meet at 7 1/2 O'Clock this evening. The Cabinet accordingly assembled at that hour; all the members present. The subject of the despatch received this evening from Gen'l Taylor, as well as the state of our relations with Mexico, were fully considered. The Cabinet were unanimously of opinion, and it was so agreed, that a message should be sent to Congress on Monday laying all the information in my possession before them and recommending vigorous & prompt measure[s] to enable the Executive to prosecute the War. The Secretary of War & Secretary of State agreed to put their clerks to work to copy the correspondence between Mr. Slidell & the Mexican Government & Secretary of State and the correspondence between the War Department & Gen'l Taylor, to the end that these documents should be transmitted to Congress with my message on Monday. The other members of the Cabinet tendered the services of their clerks to aid in preparing these copies.
Mr. Senator Houston, Hon. Barkley Martin, & several other members of Congress called in the course of the evening, & were greatly excited at the news brought by the Southern mail from the army. They all approved the steps which had been taken by the administration, and were all of opinion that war with Mexico should now be prosecuted with vigor.
The Cabinet adjourned about 10 O'Clock, & I commenced my message; Mr. Bancroft and Mr. Buchanan, the latter of whom had prepared a history of our causes of complaint against Mexico, agreed to assist me in preparing the message.
