Tycho Brahe personalities. When Tycho and Vedel returned from Leipzig in 1565, Denmark was at war with Sweden, and as vice-admiral of the Danish fleet Jørgen Brahe had become a national hero for having participated in the sinking of the Swedish warship "Mars" during the First battle of Öland (1564). Shortly after Tycho's arrival in Denmark, Jørgen Brahe was defeated in the Action of 4 June 1565, and shortly afterwards died of a fever. Stories have it that he contracted pneumonia after a night of drinking with the Danish King Frederick II when the king fell into the water in a Copenhagen
Tycho Brahe current observational data was a day off. He realized that more accurate observations would be the key to making more exact predictions. He purchased an ephemeris and books on astronomy, including Johannes de Sacrobosco's "De sphaera mundi", Petrus Apianus's "Cosmographia seu descriptio totius orbis" and Regiomontanus's "De triangulis omnimodis". Jørgen Thygesen Brahe, however, wanted Tycho to educate himself in order to become a civil servant, and sent him on a study tour of Europe in early 1562. 15-year old Tycho was given as mentor the 19-year-old Anders Sørensen Vedel, whom he eventually talked into allowing the pursuit of astronomy during