In 1945 , the liberation of Isabela commenced with the arrival of the Philippine Commonwealth troops under the Philippine Army , Constabulary and USAFIP - NL units and recognized guerrillas attacked by the Japanese Imperial forces in World War II .
In 1942 , Imperial Japanese occupied Isabela .
In 1945 , the liberation of Isabela commenced with the arrival of the Philippine Commonwealth troops under the Philippine Army , Constabulary and USAFIP - NL units and recognized guerrillas attacked by the Japanese Imperial Japanese forces in World War II .
In 1942 , Imperial Japanese occupied Isabela .