Stanley Goldyn 
The Cavalier Club [EPUB ebook] 

The year is 1618 and the beginning of the brutal Thirty Years’ War. Lieutenant Jack Channing’s life is about to be immutably altered by two events. He falls in love with a beautiful countess and witnesses an attempt on the Polish King Sigismund’s life. News reaches the court that assassination attempts on Catholic monarchs have occurred elsewhere in Europe and Jack is charged with the responsibility of finding and crushing the perpetrators — murderers that became known as the Green-Scarf Fraternity.
Mixing real historical events with fictional retelling, The Cavalier Club, is a richly detailed, impeccably researched story of adventure, bravery and love set during one of Europe’s longest and most destructive conflicts.