New England tended to sit that one out, as it did others.
In the Mexican war,
Massachusetts furnished.................1,047
New Hampshire....................................1
The other New England States........0,000
......................................................1,048
The whole number of troops contributed by the North to the Mexican war was 23,054; while the South contributed 43,630....
SOURCE: Southern History of the War, Edward A. Pollard, 1866, Vol I, Fairfax Press Edition 1978, pp. 64-5.
That is hardly surprising. The Mexican War was a war of conquest by the South to seize new territories in order to permit slavery to expand. Southern adventurers similarly contemplated efforts to seize Cuba during the antebellum period for the same reason. To secure this new slave territory, the South threatened civil war until they got the Kansas-Nebraska Act. When the free soilers were outraged by these efforts to warp the Constitution, the Southerners beat on their high chair until war finally did break out.