Philippe Berre, 57, appeared in court on Thursday, with prosecutors calling for a five-year jail sentence.
In the village of Charron, his victims say he was "friendly" and "very efficient". In March 2010, the village on the west coast of France was hit by a storm, Cyclone Xynthia, which killed over 50 people.
In the aftermath, Berre introduced himself as a civil servant working for the Agriculture Ministry sent to organise rescue and the clean-up operations.
Berre very quickly became the man in charge. He used forged documents to requisition firms, hotel rooms for firefighters. He reportedly sent rescue vehicles and all sorts of lorries for an estimated €70,000.
The court heard on Thursday that most state officials did not suspect Berre of being a fraud. During operations, he would transport them in his stolen car. The judge told the court that he had become "the head of the headquarters of the rescue operations".
At the trial, the prosecutor accused Berre of fraudulently organising rescue operations to "compensate for his narcissistic failures."