Should enemies approach the port of entry, they would be in range of the mangonel batteries at East Temple, Alamo Hill, and the Temple of Venus, which also shielded the bonded warehouse and the main, or eastern, avenue to the city. On the top of the hill, was another fortification, guarding the approaches to the Observatory, which had a complete system of defense in itself. South of the Potrero Hill fort was a harbor for the balsas. It is now a broad marsh intersected by Islais Creek. A curved canal separated two fortified hills and turned west to within the radius of the Camp of Mars. The waterway skirted the closely guarded fortification on Bernal Heights. From time immemorial Mars was not only considered the god of war but the guardian of sailors as well. On the west side of the camp, a road ran south, parallel with what is now Valencia Street direct to the port of entry. This was the only approach from the south, and was well protected by the armored hills, where the granaries and storehouses were located. Much of the food supply came by this route. Due west of Bernal Heights is a companion hill, which was garrisoned and used as a signal station, being on a line with Mount Olympus, and from the high Observatory tower news could be flashed to all the outlying stations. The center of the port of entry lined exactly with Telegraph Hill. By this means a message could be sent from Hanabusa’s quarters to Mount Olympus and Lone Mountain direct, and thence to the port of entry and Telegraph Hill, thus making it easy to command the entire situation. The horsemen’s camp lay close to Iaqua, west of the Observatory, while the spearsmen’s grounds were east. From these points were trained catapults, loaded with highly explosive lead cylinders filled with sharp spikes. Mixed with the spikes were balls containing a stifling, overpowering, deadly smell, which were exploded in the air, to shower the inhabitants, barracks and forts. * * * * * Setos saw with the eye of a military genius the advantage to himself of a sudden attack, and as a politician he felt the danger of remaining inactive in such treacherous times. With a long, hissing screech, four rockets shot into the sky from the signal-stations, electrifying some, but prostrating the spirits of those who loved law and order. Instantly, the warriors rushed pell-mell into the streets and confusion seized the populace, who ran about aimlessly, and looked into each other’s faces with half-averted eyes, like members of a family who are determined to punish one another, but not too severely. Around what is now known as Potrero Point came a fleet of thirty balsas, with the blades of the rowers flashing in the sunlight as they rocked and glided over the choppy waves of the bay. Rowing swiftly to the Rincon Hill fort, they embarked a strong force of spearsmen who were still loyal to Yermah.