The industry continued to flourish, and especially under the rule of Napoleon the Third the Cognac district reached a degree of prosperity such as had never before been known. This prosperity continued even during the period of the Franco-German war, which did not affect the region inasmuch as the operations of the war did not extend to this part of the country. It was not until 1875 that any serious check was given to the prosperity of the country. At that time, the dread disease, the phylloxera, an insect pest which attacks vines and which had already created ravages in France appeared in the Cognac vineyards and in a few years they were destroyed. In fact, the whole industry seemed to be on the verge of absolute extermination. There was one remarkable phenomenon connected with the attack of the phylloxera, namely, low-lying vineyards subject to overflow were not affected. It was found that the annual overflow of the water destroyed the life of such of the phylloxera as might have found a lodgment and thus protected the vines. The only original vineyards which still exist in the Cognac region are those which were subject to periodic overflow. Some of these vineyards have vines of remarkable size and age probably exceeding 100 years, and which are still bearing vigorously.