(3) Deeply impressed with the danger and difficulty of keeping up the lines of communication between Bayonne and Madrid, since Mina and his coadjutors had set the guerrilla war on foot in Navarre and Old Castile, Napoleon had formed a corps whose special duty was to be the keeping open of the roads, and the policing of the country-side between the frontier and the Spanish capital. This was composed of twenty squadrons of _Gendarmes_, all veterans and picked men, each with a total strength of seven officers and 200 troopers. The decree ordering their selection from among the _gendarmerie_ of Southern and Central France was published on November 24, 1809: but the first squadrons only began to pass the Pyrenees in February 1810, and many did not appear till April and May. Yet 4,000 men were in line by the summer[217]. [217] For details of this corps and its services see the monograph, _La Gendarmerie en Espagne et Portugal_, by E. Martin, Paris, 1898. (4) A few new regiments which had not hitherto been represented in the Peninsula were moved down thither. Among these were the Neuchâtel troops from Berthier’s principality, a German division from the minor states of the Confederation of the Rhine under General Rouyer[218], which went to Catalonia, the 7th, 13th, and 25th _Chasseurs à Cheval_, with two battalions of Marines. The total did not amount to more than some 10,000 men. [218] Nine battalions as follows: Two of Nassau, the others from Gotha, Weimar, Altenburg, Waldeck, Reuss, Schwarzburg, Anhalt, and Lippe; strength about 6,000 men. (5) By far the largest item in the reinforcements was composed of the 4th battalions of wellnigh every regiment which was already serving in Spain. The army which had marched across the Pyrenees in 1808 had been organized on the basis of three field-battalions to the regiment, the 4th battalion being the dépôt battalion. But Napoleon had now raised the standard to four (or in a few cases more) field-battalions, over and above the dépôt. All the fourth battalions were now existing and available; a few had served in the Austrian War, many of the others had been lying in the camps which the Emperor had formed at Boulogne, Pontivy, and elsewhere, to protect his coasts against possible English descents. Those belonging to 40 regiments already in Spain, with the full complement of 840 men each, were first ordered to cross the Pyrenees: they numbered 33,600 men: these were all at the front by May 1810. The Emperor somewhat later dispatched the fourth battalions of twenty-six regiments more to the Peninsula, giving to the temporary organization the name of the 9th Corps. This should have given another 21,840 men, and nearly did so; their gross total, when all had reached Vittoria in September 1810, was 20,231. But the 9th Corps should not be reckoned in the first 100,000 men which the Emperor set aside for the spring campaign of 1810, it was a supplementary addition[219].