Salients, re-entrants and pockets
At the Battle of Gettysburg, during the American Civil War, Union General Daniel Sickles moved his III Corps ahead of the main line of the Union army without orders. This caused him to be nearly cut off from the main army when the Confederates attacked. Sickles had held a similar position at Catherine's Furnace in the Battle of Chancellorsville two months earlier. In both cases his corps was badly mauled and had to be rescued by other units.