General Vreeland was a US Army General, and father of Veronica Vreeland.
The general was appalled to learn that Harley Quinn kidnapped his daughter, and asked for Commissioner Gordon's help to finding her. When Gordon did not meet him with the same enthusiasm in hunting the Joker's Moll, he tricked Gordon into leaving his office. He used the phone to contact the army, declaring a code red. If the police wouldn't hunt Harley down, he would.
General Vreeland ordered a tank and chased Harley and Veronica through the streets of Gotham, and was soon joined by Harvey Bullock, Boxy Bennett, and Batman. He fired several shells at Harley's car, but missed, and in the end, all pursuers, save for Batman, crashed into Harley's car. Worried about his daughter, he tried to find her among the wreckage, but she wasn't there. Harley had ejected short before, and dropped Veronica in the hands of Robin, allowing her to reunite with her father.