His episcopate coincided mostly with the emperorship of Charles the Fat and after 885 he is a leading ecclesiastical figure at the imperial court.
Geilo increased the landholdings and comital rights of the diocese of Langres immensely in his short tenure, a sign of political sagacity.
Geilo has been painted as a villain, an ambitious prelate trying to extend his see's temporal authority as far as it could go under the reign of weak Carolingians.
He quickly changed sides and supported Carloman II in 880, being confirmed in his diocese, and even staying with the king at the siege of Vienne throughout the year.
[4] The policy of episcopal empowerment in the cities of Burgundy during the 880s was largely a result of increased Viking activity in that area.