Napoleon sent Massena to occupy Straubing as he thought the Austrians might retreat along that route. Charles moved his men across the Danube at Regensburg, leaving 6,000 in the fortress to block a pursuit. Lacking time for a siege, Napoleon ordered Marshal Jean Lannes to storm the walls, succeeding at his second attempt and capturing the town by 5 pm in the Battle of Ratisbon. With the Austrian army safely in Bohemia, Napoleon marched towards Vienna. Hiller fought a series of delaying actions, attempting to buy time for the defence of Vienna. After a short fight at Wels on 2 May, Hiller gathered 40,000 troops at the bridge in Ebersberg. Massena launched a costly frontal at the Battle of Ebersberg and captured the position on 3 May, with Hiller withdrawing along the Danube. Charles attempted to move his army to defend Vienna but was outpaced by Napoleon who captured the city on 13 May. The garrison withdrew north of the Danube and destroyed the bridges behind them.