Double Chooz and a History of Reactor Theta13 Experiments

This is a contribution paper from the Double Chooz experiment to the special issue of NPB on neutrino oscillations. The physics and a history of the reactor theta13 experiments, as well as Double Chooz experiment and its neutrino oscillation analyses are reviewed.
28 pages, 11figures. The final version to be printed in Nuclear Physics B after the review. Most recent results and references were added, some typos were corrected. The title was changed to represent the contents better. Contents did not change