Taros Campaign - Troop Convoy Alpha-Four: The first Captain Nomura on the bridge of the Cerebus knew of the Tau presence was the arrival of the Io'Tar and her escorting vessels in sensor range, racing towards the convoy. The Tau attack came as a total surprise on the bridge of the light cruiser, which reacted by immediately sounding battle-stations and requesting assistance from the Hammer of Thrace. Too late, the Lunar-class Cruiser was already under orders and moving away at flank speed. She could not help.The Io'Tar opened the battle of convoy Alpha-four with a volley from her Gravitic Launchers, firing Drone missiles which scattered the convoy and escorts as they swung hard to evade the guided lock-ons. The five Castellans followed close behind, closing with their forward Railgun batteries lashing the frigates of Errant squadron. Taken off-guard, the escorts responded as best they could, weapons batteries booming out huge cannon shells and trying to find their range on the closing Tau vessels. In those first fusillades the Cerebus was hit in the engines as she swung hard to starboard. A Drone missile had locked on and could not be shaken; it found its mark. The explosion as the missile penetrated the Cerebus’ stern flashed through the engine decks, incinerating engineers, Servitors and ratings. Seriously damaged by the impact, the Cerebus ' main plasma core began to dangerously overheat, running out of control and threatening to detonate the entire ship. Captain Nomura ordered the core shut down, but that left his vessel a drifting cripple at the mercy of the Tau gunners. The Tau gunners showed little mercy that day. As Cerebus was lashed by fire, Captain Nomura ordered all to abandon ship, but refused all advice to leave the bridge himself. With their convoy leader disabled, the transports fled for safety. The cruiser Black Duke had been ordered to their aid, but was still too far away to intervene in the battle. The transports changed course to meet the incoming Dictator-class Cruiser, but their small engines where unable to outrun the pursuing Castellans, which now swarmed around them, Ion Cannons and Railgun batteries blazing, overwhelming shield generators, buckling armour plates and puncturing hulls.In the holds of their transports the Guardsmen of the 8th Brimlock Dragoons were powerless to aid in their own defence. They felt their ships roll and vibrate with each enemy near miss. They heard the engines straining at flank speed and the distant thunder of the transports’ own small cannons returning fire. The Imperius Anvil was hit amidst ships as one Castellan swept over her, a gravitic launched missile smashed through the thin side armour and into the packed holds. The massive explosion inside the cramped interior tore men apart, tossing bodies about and setting fires raging through the lower decks. In that first impact hundreds died, the fires would claims hundreds more. Fatally wounded, the stricken transport fell behind the others, stranding a third of the Brimlock regiment. Next the Prince Maud was critically hit, shields stripped away by the Tau fire, a Railgun battery volley tore through the bridge and super-structure, killing the bridge crew to a man. Unknown to the Imperial Guardsmen in the holds below, their vessel was now drifting with no captain and no one to man the helm. She was easy pickings for the Tau.To the rear Errant squadron was fighting bravely, but was now heavily outgunned by the Io'Tar. They traded bombardments, retaining the slim hope that the Black Duke would arrive to rescue them. The Lunar-class cruiser was straining every engine and reactor, racing to the rescue, but too late. Convoy Alpha-four was being annihilated by the surprise attack, and with it the 8th Brimlock Dragoons. The last of the transports were hunted down and destroyed before the Tau vessels turned about and fled back the way they had come. The Black Duke was still some hours away, and would only arrive in time to begin rescue operations. There was little to salvage except the few lucky survivors. Like wolves falling on the fold the Tau had torn the convoy apart. It is probable that they never realised that trapped within the transports thousands of guardsmen had perished as the bulkheads collapsed and hulls tore open, spilling silently screaming men out in the hard vacuum of space. The 8th Brimlock Dragoons were no more.Before being destroyed the Cerebus had launched its lifeboats, and many of these were picked up by the Black Duke. The survivors told the tale of the sudden surprise attack which had overwhelmed them. It was the first ambush of many. The grim news of the destruction of Convoy Alpha-four and the loss of an entire Imperial Guard regiment reached Admiral Kotto on the Righteous Power and Lord Marshal De Stael on Taros. It was a heavy blow for both, and Admiral Kotto set about making new plans and issuing new orders for increased protection of the convoys. The Hammer of Thrace was to continue her pursuit of the Custodian, a request was sent to the War Talon to aid the hunt. They were not to stop until the dangerous Tau vessel was destroyed. The Star of Cassiopeia and Black Duke would now be diverted to convoy close protection along with Invincis and Omna squadrons. The Tau would not find any more soft targets to ambush. The Righteous Power would remain on standby, acting as the Admiral's reserve, ready to leave orbit if required.News of the destruction of the entire 8th Brimlock Dragoons caused Lord Commander Gustavus even greater concern. He immediately ordered the transportation of any other Imperial Guard regiments to Taros to cease, much to Marshal De Stael's displeasure. Whilst the Tau fleet threatened to reap such wanton destruction it was a risk Gustavus could not run. The 19th Krieg Armoured regiment had just begun embarking for Taros, and that operation was halted. The regiment received orders to stand-down until further notice. Admiral Kotto was instructed to secure the supply lines before any more regiments would be risked in transit. Gustavus' order to the 19th Krieg regiment was never rescinded and the regiment never made it to Taros. De Stael's XI Corp was left with only three regiments: the Sarennians, the Elysians and the Cadians.The Tau's first attack had been a great success, but now they would need to attack a second convoy. The A'Rho was on the run, leading two Imperial capital ships on a long chase across the solar system. It was not until reaching the inner flare zone that she would be finally brought to battle. In subsequent weeks the lo'Tar and lo'Phi continued to harass the supply convoys, risking the bigger Imperial vessels to pick off transports. During the attack on convoy Epsilon-six, the super-heavy tanker Empress of Svedeg was crippled by Drone missiles, along with her valuable cargo of water and fuel. It was a blow that would cost the 4621st Army very dearly when the water supplies started to run out. Every convoy now ran the gauntlet; some made it through, others arrived after being damaged, some transports were destroyed altogether. Each time a ship was lost more vital supplies were lost as well.