Pelet fought in the Battle of Caldiero on 28–30 October 1805 where he was hit by a musket ball in the head. He recovered and served on Masséna's staff during the 1806 invasion of Naples, after which he was promoted captain. He went with Masséna to Poland in 1807 but was not involved in any fighting. He was wounded in the brutal fighting at the Battle of Ebelsberg on 3 May 1809. Because his troops had accomplished little during the campaign, Masséna determined to seize the bridge at Ebelsberg. In the ensuing bloodbath, the French lost 1,000 killed, 1,750 wounded and 800 captured. Austrian casualties numbered 1,000 killed, 1,000 wounded and 4,200 captured. About 1,000 wounded soldiers from both sides were incinerated when the town burned. Pelet earned an elevation in rank to major 12 days after Ebelsberg. He fought in the Battle of Aspern-Essling on 21–22 May 1809. He occupied Windmill Island on 2 July which preceded the Battle of Wagram on 5–6 July and also fought at the Battle of Znaim on 10–11 July.