What two major battles events was Ulysses S. Grant associated with?
Shiloh and Vicksburg, but there were many more: Fort Donelson, Champion's Hill, Chattanooga, The Wilderness, Spotsylvania, Cold Harbor Siege of Petersburg, Five Forks, Appomattox etc.
Ulysses S Grant was given command of the Union Army because he knew how to win battles. Following the Battle of Shiloh, Halleck had taken over in Washington. Grant had stayed with the army as it captured Tennessee and moved south to capture Vicksburg. During that campaign Grant learned how to win battles against a larger force. Grant made a number of mistakes. He did not make the same mistakes twice.