New York State played a pivotal role in the Civil War. As the wealthiest and most populous state at the time, New York led all others in supplying men, money, and materiel to the Union Army.

While united in battle to preserve the nation, New Yorkers were torn over the same issues that divided them before the war. In order for the North to emerge victorious, however, these divisions—between immigrant and native-born, rich and poor, abolitionist and anti-abolitionist, Republican and Democrat—had to be overcome.