Before the war soldiers carried muskets that could only be fired once before a soldier had to reload. They weren't very accurate until you were very close to your target. Rifles had greater range, but it was too hard to load them so they weren't used in battle until a Frenchman named Claude Minie invented a better, easier to load bullet. It was an improvement, but you still had to pause and load after every shot. By 1863 rifles that fired more than one shot before soldiers had to reload was invented. This gave the North a huge advantage over the South because the South didn't have the new guns. This is the Spencer rifle that shot 7 times before reloading.
The North used hydrogen filled balloons to fly over Confederate sites and report what they found.
The North also used ironclad boats, but the South developed submarines to try to stop them. They did sink one ironclad off the coast of SC. The Hunley a Confederate sub sank the Housatonic, but the Hunley sank too.
Railroads and telegraphs were also used in the war. In both cases the North had the advantage. The union had 24,000 miles of railroad track at the beginning of the war, and the South only had 9,000. The North also had most of the track and locomotive factories. Of course the advantages of moving troops and supplies quickly is obvious. The railroad was one technology that was extensively used after the war ended.
Abraham Lincoln was the first president to communicate using a telegraph. Again, relaying information quickly is obviously an advantage to any army. The South lacked the money and experience to have widespread telegraph usage.
In case you've forgotten, we're talking about the Civil War because Aimee Sherwood my heroine in Fortuna is in love with two men, and one of them owns a house built during the Civil War era. If you'd like to pick up a copy of Fortuna you can find it at http://amzn.to/23yoW2d