WWII merchant ships - when did they start being armed?

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By 1944 a typically armed Victory ship carried : "At the bow was a 12-pounder HA/LA gun intended primarily for use against surface vessels or surfaced submarines. At the stern, atop the deckhouse for the seamen's/firemen's messes was a 4-inch HA/LA gun that could be equally effective against surface or air attacks. Also atop the same deckhouse, on an elevated mounting immediately behind the 4-inch gun, was a Pillar Box, an anti-aircraf t rocket weapon which was armed with twenty (20) rail-launched 2-inch high explosive rockets in racks, ten (10) on each side. On some ships, a 40-mm Bofors AA or a 20-mm Oerlikon gun was an alternative. Between the bow and stern extremities of the ship where the heavy weapons were positioned, were no less than eight (8) armoured gun tubs for light automatic, primarily AA, weapons, six (6) of which were 20-mm Oerlikon AA guns. Two gun tubs were located port and starboard at the aft end of the boat deck; two were port and starboard on the wings of the upper bridge; two further tubs were situated port and starboard of the foremost deckhouse. The two remaining tubs, which were intended for Twin .50-inch machine guns (intended to counter attacks by E-boats), were port and starboard immediately ahead of the forward exremities of the captain's bridge deck. "The "armour" that afforted a measure of protection against shrapnel and small arms fire for the gun tubs was a sandwich of steel plate with a thick asphaltic filling. A similar shielding also covered the front of the navigating bridge, the ship's command centre.

"The ships' anti-aircraft weaponry was rounded out with two Fast Aerial Mines (FAM) mounted port and starboard near the funnel. Most ships additionally carried the Parachute And Cable (PAC), similar to the FAM but lacking a bomb and trailing only about 400-feet of cable, about half that of FAM. "The FAM was a strange devise which comprised a propelling rocket and some 1,000-feet of light wire cable at the end of which was afixed an explosive devise, or mine. When fired, the rocket trailed the wire cable into the air in front of the attacking aircraft. On reaching optimum altitude, two parachutes were automatically deployed, a large one at top of the cable and a smaller one at the lower end. The concept was that a strafing aircraft would fly into the trailing wire as it slowly descended. Once snagged, the wire would be dragged by the larger parachute until the mine contacted the aircraft's structure.

New one for me: I note that British lendlease LST's also carried four FAM's in 'mounts' but not American LST's did not... I cannot seem to find a photo of one of this type of ordinance; ANY ideas out there? I suspect it was a variation on the short-lived 'Z' batteries with wire/parachute mines fired from Royal battleships at aircraft; The weapon had 20 smoothbore tubes, fired ten at a time. A small cordite charge was used to ignite a rocket motor which propelled the fin-stabilized 7-inch (18 cm) diameter rocket out of the tube to a distance of about 1,000 feet (300 m), where it exploded and released an 8.4 ounces (240 g) mine attached to three parachutes by 400 feet (120 m) of wire. The idea was that an aeroplane hitting the wire would draw the mine towards itself where it would detonate. BOTTOM LINE: it was ineffective; aircraft could avoid the wires and the ordinance had been seen igniting on HMS Hood's deck during her fatal encounter with Bismark...after which the Admiralty acted to remove the weapon from all British warships. Seen mounted on turret of HMS Nelson prior to replacement by Bofors 40mm guns. As if it will work better on an LST than on a Battleship??? Well it must have been a form of ' second handmedown comfort' ordinance.