Given the question: Question: "What was the causing factor for the Greek theater to be developed in the early 19th century?"  Context: "The modern Greek theatre was born after the Greek independence, in the early 19th century, and initially was influenced by the Heptanesean theatre and melodrama, such as the Italian opera. The Nobile Teatro di San Giacomo di Corfù was the first theatre and opera house of modern Greece and the place where the first Greek opera, Spyridon Xyndas' The Parliamentary Candidate (based on an exclusively Greek libretto) was performed. During the late 19th and early 20th century, the Athenian theatre scene was dominated by revues, musical comedies, operettas and nocturnes and notable playwrights included Spyridon Samaras, Dionysios Lavrangas, Theophrastos Sakellaridis and others."  Answer:
The answer is:
Greek independence