Which 12th-century Cistercian abbot is famous for preaching the Second Crusade?

The story behind the answer

He was the towering Cistercian preacher who, at Pope Eugene III’s request, launched the Second Crusade in 1146, electrifying crowds at Vézelay and later in the German lands. His sermons and letters rallied kings Louis VII and Conrad III and thousands of followers, making monastic moral authority central to crusading propaganda.

A leading mystic and reformer, he embodied the Cistercian emphasis on austerity and authority; he also endorsed the Knights Templar in his treatise De laude novae militiae. The order’s founders, Robert of Molesme and Stephen Harding, predate the crusade; Aelred of Rievaulx was a noted Cistercian author, not the crusade’s preacher. After the campaign’s failure, he reflected on the limits of human zeal versus divine will.