In September, Jefferson Davis participated in the
Battle of Monterrey, during which he led a successful charge on the La Teneria fort.
On May 17 1847, President Polk offered Davis a federal commission as a brigadier general and command of a brigade of militia. Davis declined the appointment, arguing that the Constitution gives the power of appointing militia officers to the states, not the federal government.
What if instead of declining this commission, Davis, takes it with gratitude and is know in the South as a strong brigadier general?
In the summer of 1849, Venezuelan adventurer Narciso López, leader of a group of Cuban revolutionaries, visited Davis and asked him to lead the expedition, offering an immediate payment of $100,000 (worth more than $2,000,000 in 2013), plus the same amount when Cuba was liberated.
In OTL Davis turned down the offer, stating that it was inconsistent with his duty as a senator.
What if, now he is a brigadier general, he accepts the offer, assisting López in his filibusting mission. They gained local support, who answered Davis's appeals at once and are able to liberate Cuba from Spanish rule, becoming the first Military-Governor Protectorate over Cuba, from 1850-1853.
In 1852, Franklin Pierce won the presidential election, and in 1853 makes General Davis his Secretary of War, a position he will hold until 1857. For the next four years, Davis, would go to Southern military bases supporting his life long friend, Robert E. Lee who was Superintendent of the United States Military Academy.