She was the wife of Erard de Brienne-Ramerupt, who encouraged her in 1216 to claim the county of Champagne which belonged to her cousin Theobald IV, who was still a minor.

This provoked the conflict with Theobald's mother, the Regent, Blanche of Navarre, which erupted into open warfare, and came to be known as the Champagne War of Succession.

Philippa was born in about 1197 in the Holy Land, the youngest daughter of Queen Isabella I of Jerusalem and Count Henry II of Champagne.

[4] Shortly after their marriage, Erard encouraged Philippa to claim her father's county of Champagne which had succeeded to her cousin Theobald IV, who was still a minor.

Supporters of Blanche also convinced a papal legate that the divorce between Queen Isabella and her first husband, Humphrey IV of Toron had been invalid, thus making Philippa and her sister Alice illegitimate.

The war finally ended upon Theobald reaching his majority in 1222, and in April of that year, Philippa was persuaded to renounce her claim to Champagne on behalf of her cousin.