Region II or Cagayan Valley is located in northeastern Luzon between the Cordilleras and Sierra Madre mountain ranges. It has 5 provinces and 3 cities with its regional center in Tuguegarao City and commercial center in Santiago City. The long Cagayan River runs through the region and empties into the Luzon Strait. During World War II, Japanese forces retreating from American and Filipino troops dug in at Balete Pass (now called Dalton Pass) in Nueva Vizcaya and held out for 3 months before being driven out. Now, Cagayan Valley is the largest producer of tilapia in the Philippines, especially in the provinces of Nueva Viz