In July 1890, Bob Dalton, Grat, and Emmett were accused of stealing horses near Claremore to sell them in Kansas. With a posse close behind of them Bob and Emmett left the territories for California where brother Bill was residing. Grat was arrested for the crime but would gain his release because of a lack of evidence. He would join his brothers in California. On the night of February 6, 1891 the Daltons raided a train operated by the Southern Pacific Railroad, near Alila, stealing $60,000. The boys were accused of the crime causing Bob and Emmett to flee the state, with a posse after them, while Grat and Bill were arrested. Grat would be found guilty on July 3, 1891 after a jury trial. Bob and Emmett retreated to the Indian Territories, but the law was still after them, so they decided to hide themselves. When Emmett worked, previously, at the Bar X Bar Ranch he became friends with cowboys Bill Doolin and Bill Power. Acquaintances of Emmett from other ranches included Charlie Pierce, George Newcomb, Charlie Bryant, and Richard Broadwell. Bob, as gang leader, decided they needed reinforcements and the future gang recruits were tough men who would help the brothers rob banks and trains throughout the Oklahoma Territory over the following 18 months. The Dalton boys, at first, connected with Bryant and Newcomb in Wharton, Oklahoma Territory to rob a train in May 1891 earning $1745. Shortly after the robbery, Bryant fell ill and was taken to Hennessey to see a doctor. After being spotted and arrested by Deputy Marshal Ed Short, during an escape attempt, they would kill each other.

On the night of September 15, 1891 they next robbed was the KATY train at Leliaetta, near Wagoner, Indian Territory. Bob and Emmett Dalton led Newcomb, Powers, Broadwell, Pierce and Doolin on the raid. The gang stopped and boarded the train and then robbed $2500 from the express car. Grat escaped from jail on Sept. 18 while awaiting sentence in California. He promptly returned to Oklahoma to rejoin his brothers. At the end of May 1892 the three Dalton brothers led Pierce, Newcomb, Powers, Broadwell, and Doolin on another train robbery. At the Red Rock train station, June 1, 1892, the gang positioned themselves to await an approaching train. A train entered the station with its coaches dark, which alerted the gang to a problem, so they allowed it to continue. A second train suddenly arrived which the gang boarded as it stopped at the station. They gang boarded it and robbed it but only collected $50. The gang would later discover that the first train carried armed guards protecting $70,000 of the Sac and Fox Nation annuity. The gang would make its last train robbery at Adair, Indian Territory on July 14, 1892. The train was again loaded with deputies, but the gang was quick and quiet enough not to disturb the marshals until the job was nearly completed. Exiting from the train the marshals would engage the gang in a violent but short gun battle. The battle would claim the life of an innocent bystander and wound another. The Dalton Gang would escape without casualties but with the cash.

The gang split to pursue their own goals after the Adair raid. Bob and his brothers were deeply concerned with the pressure put upon them by the law. They decided to make one last robbery to earn enough money to leave the country. Their plan was to rob two banks in the same town at the same time to get the money and to also make history for accomplishing something that no other outlaw gang had even attempted. Their target was their old hometown of Coffeyville, Kansas. Early on Oct. 5 1892, Bob, Grat, Emmett, Powers and Broadwell entered Coffeyville. Tying up their horses in the alley across from the banks, they walked across the street dividing into two groups before entering the Condon National Bank and First National Bank. Well known by the townspeople they were recognized and an alarm was given. Townsmen quickly armed themselves with guns from the local hardware stores and took positions to defend their town. As the Dalton Gang began their escape a gun battle erupted that killed gang members and four town citizens. The lone survivor among the gang, Emmett, was seriously wounded receiving 23 gunshot wounds. He would stand trial for the bank robberies after recovering. Sentenced to life in prison he would be granted a pardon by the governor after 14 years.

Deputy Marshal Heck Thomas would remember Bob Dalton as the most accurate shot he had ever seen. Dalton is buried at the Coffeyville, Kansas Cemetery under a group marker for himself, his brother Grat, and Bill Power. The actor Forrest Tucker played Bob Dalton in the 1963 episode “Three Minutes to Eternity” of the syndicated western television series Death Valley Days, a dramatization of the simultaneous bank robberies in Coffeyville. Tom Skerritt portrayed the surviving Emmett Dalton; Jim Davis was cast as Grat Dalton. The episode was narrated by Stanley Andrews, known as “The Old Ranger”. In 1975 Bob Dalton was played by the actor Robert Conrad in the TV movie western The Last Day.