[4] When Louis succeeded his father as emperor in 814, Helisachar accompanied him to Aachen and became archchancellor of the empire, an office in which he continued until at least August 819.
[9] In 822, Archbishop Agobard of Lyon addressed two letters to Helisachar requesting him to bring a matter before the emperor.
[14] Although Nithard presents Helisachar as out of favour until 833, Louis sent him on a justicial mission to the Breton March in the autumn of 830.
After his restoration, Louis sent Helisachar as missus to Maine, fulfiling a request of Bishop Aldric of Le Mans.
[9] Freculf of Lisieux dedicated the first volume of his universal chronicle to Helisachar, whom he praises in a letter for his "insatiable love of wisdom".
[16] Helisachar's surviving writings are a preface to the epistolary of Alcuin and a letter to Nimfridius [fr], written probably at Angers between 819 and 822.
[8] In his letter to Nimfridius, Helisachar refers to his work on an antiphonary for the officium intended to reconcile the competing Roman and Frankish usages.