What action did the smith-connally act of 1943 make illegal?

I believe that the best answer for this question would be that the Act prohibited unions from contributing to politicians in federal elections. It was created in a rush after hundreds of thousands of coal miners went on strike and demanded a wage increase due to high wartime inflation. Beyond prohibiting union contributions, the Act also allowed the government to forcibly take and manage industries threated by strikes during wartime. Hope this helps.