On the right the I Canadian Corps on 20 September broke the German positions on the Ausa river and into the Lombardy Plain and 3rd Greek Mountain Brigade entered Rimini on the morning of 21 September as the Germans withdrew from their positions on the Rimini Line behind the Ausa to new positions on the Marecchia. However, Kesselring's defence had won him time until the onset of the autumn rains. Progress for the Eighth Army became very slow with mud slides caused by the torrential rain making it difficult to keep roads and tracks open, creating a logistical nightmare. Although they were out of the hills, the plains were waterlogged and the Eighth Army found themselves confronted, as they had the previous autumn, by a succession of swollen rivers running across their line of advance. Once again, the conditions prevented Eighth Army's armour from exploiting the breakthrough, and the infantry of British V Corps and I Canadian Corps (joined by the 2nd New Zealand Division) had to grind their way forward while von Vietinghoff withdrew his forces behind the next river beyond the Marecchia, the Uso, a few miles beyond Rimini. The positions on the Uso were forced on 26 September, and Eighth Army reached the next river, the Fiumicino, on 29 September. Four days of heavy rain forced a halt, and by this time V Corps was fought out and required major reorganization.