Napoleon established headquarters at Kovno and remained in that town for three days.
Until Kovno everything had gone according to the plans, but the following days were to reveal much tougher challenges in terms of climate and road quality. Lieutenant Mertens from Wuerttemberg, who was with III Corps gives this account:
"Until Ianovo [a town north of the Kovno-Vilna road], the heat was oppressive and the dust stifling. In the afternoon, the thunder would roll and we were drenched to the skin. On 28 June, the rains settled in and the first order of the day was to build some huts. Our exertions on this and the days following were the reason for the outbreaks of dysentery and influenza, which soon ran through the rank without let-up and thinned them more effectively than enemy shot. The rain held on through the 29th and left us in dire straits. On the 30th, we left our swamp-camp at the crack of dawn and on the 1st of July, many more men and horses fell victim to the mud. On the 3rd, the sun greeted us again, but the dysentery raged so badly that several hundred sick had to be brought to Maliaty, where a field hospital had been hastily established."