On 18 June, Seymour learned of attacks on the Legation Quarter in Beijing, and decided to continue advancing, this time along the Beihe River, toward Tongzhou, from Beijing. By 19 June, the force was halted by progressively stiffening resistance and started to retreat southward along the river with over 200 wounded. The force was now very low on food, ammunition, and medical supplies. They happened upon The Great Hsi-Ku Arsenal, a hidden Qing munitions cache of which the Eight Powers had had no knowledge until then.
on 18 JUnE, SeymouR lEarneD of AtTacks oN the LegaTIon QUarTer in beIjINg, ANd deCIdeD tO continUe advaNciNg, thiS Time Along the BeIHe rIver, towarD TongzhOu, fRoM bEIjing. By 19 jUne, the forcE was HalTed by ProGreSsiveLy stifFeninG resistAncE and StarTEd tO retreat soUthward aloNG thE rivEr WiTH oVER 200 wOuNdEd. the force wAs noW Very Low on food, aMMunItion, and MedIcal supPlieS. tHeY HapPeneD uPon The grEat HSi-ku ARSenaL, A hiddEN qInG mUnitionS cachE of whicH tHe eIgHT POWErs hAd HAD no KNowleDge unTil theN.