SOUTHERN UKRAINE — In dimly lit hospital rooms in southern Ukraine, soldiers with severed limbs, shrapnel wounds, mangled hands and shattered joints recounted the lopsided disadvantages their units faced in the early days of a new offensive to expel Russian forces from the strategic city of Kherson. The soldiers said they lacked the artillery needed to dislodge Russia’s entrenched forces and described a yawning technology gap with their better-equipped adversaries. The interviews provided some of the first direct accounts of a push to retake captured territory that is so sensitive, Ukrainian military commanders have barred reporters from visiting the front...