Tannenberg is the German name for the formerly East Prussian, now Polish, city of Olsztynek[?]. It is still widely known by its German name due to two famous battles fought in its vicinity, in 1410 and 1914.
... known Christian books on devotion.
I. Life, Minor Writings
Thomas à Kempis, German mystic and author of the "Imitation of Christ," was born at Kempen[?], Germany ...