CHACO, a territory of northern Argentina, part of a large district known as the Gran Chaco, bounded north by the tern tory of Formosa, east by Paraguay and Corrientes, south by Santa Fe, and west by Santiago del Estero and Salta. The Ber mejo river forms its northern boundary, and the Paraguay and Parana rivers its eastern. Pop. (193o) 50,000; area, 150,000 sq. miles. Northern Chaco has long been the subject of dispute be tween Bolivia and Paraguay. Armed clashes over its possession began in 1928 and gradually developed into open war. All efforts of other states and the League of Nations to mediate were un availing. And the belligerents continued their 4loody struggle in spite of a seeming bankruptcy on both sides. Paraguay on the whole, proved the more successful in arms. Finally a truce was arranged on June 14, 1935, followed by a formal peace agreement signed at Buenos Aires, Aug. 21, 1936.