A few weeks prior to the Englishmen's arrival, a powerful combination of the Arab tribes lying to the east and west of Croixilia had threatened the city, and outposts were formed on all sides. The north side was fairly secure from assault, owing to the natural defences afforded by the river and the "plain of pitfalls", but in order to be warned of a possible junction of the enemy on that side, the Croixilian outposts had been advanced well into the desert; and it was at this station that the English fugitives had fallen in with Garth and his comrades. For the next week or two Reeves and the two lads were received in daily audience by Sir Jehan, who began to realize that their knowledge of the modern science of war was an asset that would be of immense value to him in the threatened invasion. For his part, Reeves readily consented to do his best for his entertainer. He realized that, with the Arabs holding the western plains, any attempt to follow the river would be hopeless; and until the way was clear it would be well to remain in comparative security in Charleton, rather than risk a tedious journey through an unknown and hostile country. One of his first acts was to establish a powder factory, sulphur and saltpetre being found in the hills lying to the south of the city. Under direct supervision the serfs proved excellent and intelligent workmen, and soon Reeves had the satisfaction of knowing that there was a sufficient quantity of explosives to last throughout a protracted siege. His next thought was to provide firearms. Up to the present the total number available amounted to four--the three flintlocks and the automatic pistol. For the latter only thirty-five cartridges remained, and, failing a proper capping machine, the correspondent realized that a further supply of ammunition was unobtainable. He therefore directed his attention to the manufacture of flintlock guns; but here he was foiled. Although he took to pieces one of the weapons, and carefully explained the working parts, the artisans replied that the work was beyond them. Flints, too, were unobtainable, so Reeves decided to construct a number of small cannons, and mount them at convenient positions upon the wall. This was accordingly done, for the Croixilians were fairly expert in bell-founding, and were able to construct moulds to the plans that Reeves drew for their guidance. Day and night the great wood-fed forges were kept constantly at work, till forty pieces of muzzle-loading, smooth-bore, firing a six-pound ball, were ready for use. Still not satisfied, the indefatigable Englishman directed his attention to the manufacture of cast-iron shells, which were filled with a rough-and-ready fuse composed of thin folds of damp cotton sprinkled with powder.