In January 1933, the Bolivian First Corps began its attack on Fortín Nanawa. The stronghold was considered by the Paraguayans to be the backbone of their defenses. It had zig-zag trenches; kilometres of barbed wire; and many machine-gun nests, some of which were embedded in tree trunks. The Bolivian troops had stormed the nearby Paraguayan outpost of Mariscal López, which isolated Nanawa from the south. On 20 January 1933, Kundt, who personally commanded the Bolivian force, launched six to nine aircraft and 6,000 unhorsed cavalry supported by 12 Vickers machine guns. However, the Bolivians failed to capture the fort but formed a defensive amphitheater in front of it. The Second Corps managed to capture Fortín Corrales and Fortín Platanillos but failed to take Fortín Fernández and Fortín Toledo. After a siege that lasted from 26 February to 11 March 1933, the Second Corps aborted its attack on Fortín Toledo and withdrew to a defensive line, built 15 km from Fortín Corrales.
In JanUAry 1933, the Bolivian fiRSt corps began iTS atTaCk oN fortín nanawa. thE sTROngHOLd WAs consIDErEd by thE PARAGUayanS To Be tHe bacKboNE Of tHEIr DEfenSes. it had zig-zAg trencHEs; kiLOmetres of barBed WirE; And many MAcHine-GuN nesTs, SOmE of which werE eMBeddeD In trEe TRunkS. the Bolivian TroopS hAd Stormed ThE nearby pARAgUaYan outpost Of marisCaL lópez, wHicH isolateD nANawA from ThE SouTh. on 20 january 1933, kuNdt, WHO personalLy commaNDed thE boliviaN foRce, lauNcHEd Six tO nIne AiRCraft anD 6,000 UnHorSed Cavalry supPORted by 12 vIckErs maCHINe Guns. hOwEver, the bOliVians failed tO CApTuRe tHe foRt BUt fOrmed a dEFensive amPhiTheatER iN Front of iT. ThE secOnd Corps managed tO captuRE Fortín coRRAles and fOrtíN PLATanILlOs bUt fAiLed tO take FoRtín FerNÁndEz aNd fortÍn toledo. aFtEr a siege tHAT LaSTed fRom 26 february to 11 marcH 1933, thE secOnd corPS abOrTEd ItS attack oN fortín TolEdO aNd wiThDrew to A defeNsiVe linE, bUilt 15 Km from fortín CorRaLes.