Clement proclaimed a crusade in 1343, but nothing was accomplished beyond a naval attack on Smyrna on 29 October 1344. He also had a role in the Hungarian invasion of the Kingdom of Naples, which was a papal fief; the contest between Louis I of Hungary and Joanna I of Naples, accused of ordering the assassination of her husband and the former's brother, concluded in 1348 in a trial held in Avignon, at which she was acquitted. Among the other benefits, Clement took advantage of the situation to obtain by her the rights over the city of Avignon.