Why did Pope Innocent III place France under an interdict in 1200?

In January 1200, Pope Innocent III placed France under an interdict due to King Philip II’s marital conduct.1

After the death of his first wife, Isabella of Hainaut, in 1190, Philip married Ingeborg of Denmark in 1193. However, he sought to separate from her almost immediately and procured an annulment from an assembly of French bishops later that year. Philip subsequently married Agnes of Meran in 1196.1

Denmark appealed to Rome regarding the repudiation of Ingeborg, and while Pope Celestine III had countermanded the annulment in 1195, he died before he could enforce his decision. Upon his accession, Innocent III took a firmer stance, demanding that Philip take back his wife. The resulting interdict in 1200 forced Philip to submit in September of that year, though he only pretended to be reconciled with Ingeborg and kept her in semicaptivity for many years thereafter.12