This dissertation explores the circumstances that inspired the Infanta Isabel Clara Eugenia, Princess of Spain, Archduchess of Austria, and Governess General of the Southern Netherlands to commission Peter Paul Rubens's "The Triumph of the Eucharist" tapestry series for the Madrid convent of the Descalzas Reales. It traces the commission of the twenty large-scale tapestries that comprise the series to the aftermath of an important victory of the Infanta's army over the Dutch in the town of Breda. Relying on contemporary literature, studies of the Infanta's upbringing, and the tapestries themselves, it argues that the cycle was likely conceived as an ex-voto, or gift of thanks to God for the military triumph. In my discussion, I highlight previously unrecognized temporal and thematic connections between Isabel's many other gestures of thanks in the wake of the victory and "The Triumph of the Eucharist" series. I further show how Rubens invested the tapestries with imagery and a conceptual conceit that celebrated the Eucharist in ways that symbolically evoked the triumph at Breda.

My study also explores the motivations behind Isabel's decision to give the series to the Descalzas Reales. It discusses how as an ex-voto, the tapestries implicitly credited her for the triumph and, thereby, affirmed her terrestrial authority. Drawing on the history of the convent and its use by the king of Spain as both a religious and political dynastic center, it shows that the series was not only a gift to the convent, but also a gift to the king, a man with whom the Infanta had developed a tense relationship over the question of her political autonomy. I argue that when Isabel presented the tapestries to the Descalzas Reales she intended them to assert her power and, moreover, compel its reciprocation. This interpretation relies on archival documents that show that Isabel frequently gave religious gifts to establish relationships of reciprocity; the simultaneously religious and political functions the convent served the Spanish royal family; as well as on the tapestries themselves.