The terrible Roman summer caught the imperial army unprepared. With the heat, the Anopheles mosquitoes that populated the Pontine Marshes south of Rome moved toward the city and carried the malaria bacillus. The first cases broke out on August 2nd. A week later, the first deaths occurred among Frederick Barbarossa’s Templars. The list of noble victims was impressive: Duke Frederick Rotherburg, Duke Welf the Younger of Bavaria, Theobald, brother of King Vladislaus of Bohemia, the Counts of Sulzbach, Halremonth, and Leipzig, the nobleman Ludolf of Dassel, Archbishop Daniel of Prague, and the bishops of Verdun, Regensburg, Basel, and Strasbourg, as well as Frederick’s chief advisor, Rainald of Dassel, Archbishop of Cologne. As many as 20% of the imperial army was fatally affected: between 2,000 and 3,000 dead. Morale plummeted. Many linked malaria to Frederick’s assault on St. Peter’s Basilica, as divine punishment.
