Krieg is a typical One Piece villain who displays cruel tendencies using a huge arsenal of weapons and overwhelming odds. He is used to winning and being able to topple any force that goes up against him; this led to his failed attempt to conquer the Grand Line. However, his constant victories and reliance on weapons and odds made him overconfident.
He displays some realization that his crew is an important aspect to his efforts and he makes sure they are fed to regain their full strength after Mihawk's onslaught.  However, Don Krieg does not care for his crew and bullies them to fear him as their captain; he punishes those who fail him or show signs of weakness often with death.
AbilitiesKrieg, of the Pirate Armada, was considered (in military strength) the most powerful pirate in the East Blue. Although Krieg had a lower bounty than Arlong, his fleet of 50 ships and over 5,000 pirates, combined with active pillaging, forced the Marines to view Krieg as a greater threat. Though it was commented by Luffy that Krieg's fleet were not all that powerful, more that there was just so many of them they could overwhelm their opponent.
His most potent weapon has always been his talent for skulduggery, which seems to have no bounds. Krieg also claimed to be the strongest man in the world, while this is clearly an over-estimate on his part, he is certainly formidable in physical combat. He possesses superhuman strength as he is shown as being able to take cannonballs without moving an inch, and when he easily lifts and throws the Sabagashira No. 1 that Patty and Carne attacked him in.
He also has knowledge of Devil Fruits, as shown when he witnessed Luffy's ability stretch, noting that the Grand Line is supposed to be filled with such people.
WeaponsKrieg wears a gilded suit of steel armor that is filled with hidden weapons, including the dreaded MH5 (a built-in weapon in his shield that shoots off poison-gas bombs), diamond knuckles (for hand-to-hand combat), spike-covered cape and a giant battle spear that explodes with every swing. The tip of the spear was ultimately shattered by Luffy, making it a bomb on a large stick. Krieg's armor is forged of Wootz steel. He can even convert his shield into a Gatling gun that fires sharp metallic stakes that impale Luffy, bypassing his Gomu Gomu no Mi abilities.
Past StoryWhen he was first starting out as a pirate, he stole a Marine ship and, under the guise of a Marine flag, approached towns without suspicion. Krieg's massive armada gave him the title, "Pirate Admiral Don Krieg".
Don Krieg made a trip to the Grand Line with his fleet, hoping to find the One Piece. On his seventh day in the Grand Line, however, his ships were completely destroyed by Juracule "Hawkeyes" Mihawk, one of the Shichibukai. With only one ship escaping through sheer luck but in terrible condition, Krieg returned defeated to the East Blue.
Baratie ArcKrieg soon learned of the Baratie, a restaurant that floats at sea. When he first saw the fish-shaped ship, he knew that it would be the perfect guise, for no one would suspect it of being filled with pirates. With the Baratie as a trap, Krieg planned to rebuild his Armada and once again head out into the Grand Line. He also wanted to use Zeff's journal as a guide to avoid the same fate twice on that sea. Unfortunately for Krieg, he arrived at the same time the Straw Hat Pirates were at the restaurant. After a long and intense battle on the wreckage of his old ship, Krieg was eventually defeated by Luffy. It is important to note that without the outside interference Luffy received he would have won, as at the end of their fight Krieg was knocked out, but Luffy was thrown into the sea in an iron net and would have died had he not been rescued by Sanji.
Even with this loss, he subconsciously wouldn't give up by rising to his feet while unconscious, and it took his whole crew and a final punch in the gut from his first mate Gin to finally drop him. However, he is still alive, but it is unknown if he will continue to pursue Luffy when he awakes.
Major Battles* Don Krieg's Pirate Armada vs. Dracule "Hawkeyes" Mihawk
* Don Krieg vs. Baratie chefs
* Don Krieg vs. Luffy