in which decade of the nineteenth century did the american civil war take place

The American Civil War took place in the 1860s, specifically from 1861 to 1865.

The American Civil War took place in the 1860s, specifically from 1861 to 1865.

The American Civil War took place from 1861 to 1865, which means it occurred in the 1860s. To determine the decade, you can simply consider the first two digits of the year the war started. In this case, the year 1861 tells us that the Civil War happened in the 1860s.