Richard is an employee of the Dun Construction Corp. While delivering materials to a construction site, he carelessly backs Dun's truck into a passenger vehicle driven by Green. This is Richard's second accident in six months. When the company owner, Dun, learns of this latest accident, a heated discussion ensues, and Dun fires Richard. Dun is so angry that he immediately writes a letter to the union of which Richard is a member and to all other construction companies in the community, stating that Richard is the "worst driver in the city" and that "anyone who hires him is asking for legal liability." Richard files a suit against Dun, alleging libel on the basis of the statements made in the letters.

Did Dun defame Richard? Why?