Solomon felt it incumbent on him to secure his land, and not merely to adorn the metropolis by splendid buildings, but to make it inaccessible to attack. To protect northern Israel against Rezon and Damascus he fortified Hazor, whose king had once so grievously oppressed Israel, and Baalath; to protect the western border he fortified Megiddo, Gezer, and Beth-horon.[344] The defensive works which David had added to the old fortifications of the metropolis he enlarged and extended. The gorge which, running from north to south, divided the city of Jerusalem on the western height from the citadel of Zion on the east he closed towards the north by a separate fortification, the tower of Millo. By another fortification, Ophel, he protected a depression of Mount Zion between David's palace and the new temple, which allowed the citadel to be ascended from the east. The space over which the city had extended on the western height opposite the temple, in consequence of the growth of a suburb there towards the north, the lower city, he surrounded with a wall.[345] He raised the number of the chariots of war, which David had introduced, to 1400, for which 4000 horses were kept. He formed a cavalry force of 12,000 horses, he built stables and sheds for the horsemen and chariots. If we include the body-guard, the standing army which Solomon maintained may very well have reached 20,000 men.[346] The excellent arrangement of his military means and forces must have contributed to make Israel respected and to preserve peace in the land. In Solomon's reign, so we are told in the Books of Kings, every one could dwell in peace under his own vine and his own fig tree.[347] This peace from without, united with the peace which the power and authority of the throne secured in the country, must have invigorated trade, favoured industry, and considerably increased the welfare of Israel. The example of the court, the splendour and magnificence of which was not increased by buildings only, made the wealthy Israelites acquainted with needs and enjoyments hitherto unknown to their simple modes of life. If hitherto the Israelites had sold to the Phenicians wine and oil, the wool of their flocks, and the surplus products of their lands for utensils and stuffs, the finer manufactures of the Phenicians now found a demand in Israel. If the king of Israel was friendly to the Phenicians, he allowed them a road by land through his territories to Egypt; now that the Ammonites, Moabites and Edomites had been subjugated he could close or open the caravan road past Rabbath-Ammon, Kir Moab, and Elath to South Arabia (I. 320), and when Tadmor was in his hands he could permit or prohibit a road to the Euphrates beside that past Damascus. Solomon prohibited none of these; on the contrary, he promoted the intercourse of the merchants by erecting resting-places and warehouses on all the lines of traffic which crossed his dominions.[348]