How does an effective argumentative essay address counterclaims

In your thesis statement, is one way that I am used to doing it. For example, say you are doing the causes of the American Civil War and you have to say which cause is most important. Your statement could be something like this:

Although The Compromise of 1850, which lead to the Fugitive Slave Act, is a significant cause of the American Civil War, the birth of the Republican political party is the most important cause because it inspired the death of the Whig Party, created deep sectional differences between the North and the South, and lead to Abraham Lincoln becoming president in 1860.
Hope this helps!