Jacob Grimm had many different government offices

Prior to delving into linguistics, Jacob Grimm held a variety of government roles. Jacob traveled to Paris with Savigny in 1805 to conduct research on legal writings from the Middle Ages; the following year, he was appointed secretary to the Kassel war office. Wilhelm's health prevented him from working regularly until 1814. Following the French invasion in 1806, Jacob was appointed private librarian to King Jérôme of Westphalia in 1808 and then auditor of the Conseil d'État the following year. After Napoleon's defeat, however, he returned to Hessian service in 1813.

Jacob Grimm twice traveled to Paris (1814–1815) while serving as the legation's secretary to retrieve priceless literature and artwork that the French had plundered from Hesse and Prussia. He participated in the Vienna Congress from September 1814 to June 1815. Jacob joined Wilhelm there in 1816 after Wilhelm had already taken on the position of secretary at the Elector's library in Kassel (1814).

By that time, the brothers had definitely given up pursuing a legal profession in favor of solely literary studies. They built the foundations for their lifelong interests in the years they lived frugally and worked steadily.