Task: Question Generation
Input (English): Passage: The Portuguese tried again to put their preferred candidate on the throne of Kandy as a client ruler. This time it was Dona Catarina, a Kandyan princess who had been entrusted to the care of the Portuguese and brought up in a Catholic European style. She was then aged ten or twelve. Pedro Lopes de Sousa led a force of about 20,000 in an invasion of Kandy, of which one thousand were Portuguese troops , 15,400 native Lascarin allies, 47 elephants used as pack animals, and the remainder Badaga mercenaries from India and coolie labourers. The initial number of opposing Kandyan forces is unknown, but is estimated at 10,000. The defenders held a distinct advantage in the terrain, as Kandy is a mountainous region and the invading force would be forced to traverse well-defended mountain passes. The Portuguese stormed the pass at Balana with heavy losses, after which the Kandyan forces began to retreat before the invaders. The Portuguese were able to enter the capital Kandy without resistance, finding it abandoned by King Vimaladharmasuriya I. Dona Catarina was crowned as the new ruler of the Kingdom of Kandy. However she and her Portuguese advisers were unpopular rulers, particularly after rumours spread that she was to be married to a Portuguese husband . Vimaladharmasuriya's forces engaged in guerilla tactics, attacking Portuguese foraging parties and cutting off lines of supply and communication. A large Portuguese-Lascarin raiding party of 3,000 men was surrounded and destroyed in the Uva region. Shortly thereafter, evidence was found that Jayavira Bandara Mudali, one of the Lascarin chieftains, was preparing to betray the Portuguese to Vimaladharmasuriya. Part of this evidence was later shown to be fabricated by Vimaladharmasuriya, but Jayavira was killed as a traitor before this was realised.
Output (English): What was the terrain of battle most used?