Dumouriez then visited Italy and Corsica, Spain and Portugal, and his memoranda to the duc de Choiseul on Corsican affairs at the time of the Corsican Republic led to his re-employment on the staff of the French expeditionary corps sent to the island, for which he gained the rank of lieutenant-colonel. In 1767 Choiseul gave Dumouriez a military command as deputy quartermaster general to the Army of Corsica under the Marquis de Chauvelin. After this, he became a member of the Secret du Roi, the secret service under Louis XV, which gave full scope to his diplomatic skills. In 1770 he undertook a mission into Poland to the Confederation of Bar, where, in addition to his political business, he organized a Polish militia for the War of the Bar Confederation. On 23 May, his Polish soldiers were smashed by the Russian forces of General Alexander Suvorov in the Battle of Lanckorona. The fall of Choiseul (1770) brought about Dumouriez's recall. In 1772, upon returning to Paris, Dumouriez sought a military position from the marquis de Monteynard, Secretary of State for War, who gave him a staff position with the regiment of Lorraine writing diplomatic and military reports. In 1773, he found himself imprisoned in the Bastille for six months, apparently for diverting funds intended for the employment of secret agents into the payment of personal debts. During his six months of captivity Dumouriez occupied himself with literary pursuits. He was then removed to Caen, where he remained in detention until the accession of Louis XVI in 1774. Dumouriez was then recalled to Paris and assigned to posts in Lille and Boulogne by the comte de Saint-Germain, the new king's minister of war.