The major impact of technology on World War I (WWI) was that it made the war much more difficult for the infantry soldiers who did most of the fighting. The new technologies led to trench warfare and the lack of new tactics led to massive slaughter at the hands of the new technology.
New technology in the form of machine guns and rapid-fire artillery gave a huge advantage to any army fighting on the defensive in this war. When the war settled down into stalemate on the Western Front, each side had really good defensive positions with their machine guns and their artillery.
Technology also had other impacts. Technology in the form of tanks and airplanes helped to eventually end the conflict. However, the main impact of new technology was to make this a war that resulted in huge numbers of casualties due to the advantages enjoyed by defenders.