Was the Mexican War the first battle of the US Civil War?
The Mexican, or its other name, the Mexican-US War, was in 1846. There is no direct connection to the US Civil War, other then that many of the generals of the Civil War, fought together and came to know each other.
It would be fair to say that the first armed conflict that led to the US Civil War was in Charleston, South Carolina. Two reasons standout, one is that US President Lincoln had to believe it was an armed conflict, however, if he thought it was a war, he would not have called for only 75,000 volunteers to enlist for three months. Clearly he expected this rebellion to swiftly be ended and never reach the…
There was no real "first battle" of the Civil war because it started in different states after different battles. For example, the first official shot fired was at Fort Sumter when the confederates attacked unprepared and expecting union soldiers. The first big battle of the Civil War was the first battle of Bull Run/Manassas.