兵(へい)士(し) heishi達(たち) tachiは wa警(けい)戒(かい) keikaiし shiながら nagara国(こっ)境(きょう) kokkyouに ni向(む)か()っ()て() mukatte進(すす)ん()だ() susunda。 The soldiers advanced toward the border while staying on guard. Literal Soldiers [topic-は] be-vigilant [while-ながら] border [toward-に] headed-toward advanced. ~ながら connects two simultaneous actions by the same subject — 警戒しながら means 'while being vigilant.' ~に向かって marks the direction of movement. Both are common constructions in narrative. military~に向かって (toward)~ながら (while doing)
兵(へい)士(し) heishi達(たち) tachiは wa警(けい)戒(かい) keikaiし shiながら nagara国(こっ)境(きょう) kokkyouに ni向(む)か()っ()て() mukatte進(すす)ん()だ() susunda。 The soldiers advanced toward the border while staying on guard. Literal Soldiers [topic-は] be-vigilant [while-ながら] border [toward-に] headed-toward advanced. ~ながら connects two simultaneous actions by the same subject — 警戒しながら means 'while being vigilant.' ~に向かって marks the direction of movement. Both are common constructions in narrative. military~に向かって (toward)~ながら (while doing)