Edith Windsor filed suit seeking that the Defense Of Marriage Act was unconstitutional, which would make her the plantiff. The Bipartisan Legal Advisory Group, or BLAG was appointed by the House of Representatives to defend them in court, making them the Defendant. Hope this helps!
Steel was a necessary material for many new industries, such as the railroads, tool making, construction. Also, many industries were needed to support the steel industry, such as coal mining, and iron ore mining.