Answer: In 1862, Congress mandated that civil servants and military personnel take an Ironclad Test Oath that they had never voluntarily aided the Confederacy. As Reconstruction evolved, the Ironclad Oath emerged as the strictest of several possible standards for the readmission of Southerners into the political life of the Union. So basicly the oath was to stay loyal to the union, and never the confederates.
Hope this helps!
