SENJO<br/><br/>The rising ground we were on was at the south-west corner of the compound and the Leftenant had secured a tactically sound patch of dirt. There was an oval space about twenty metres by ten aligned long-axis parallel to the north-south ridge behind us. Several large rocks defined the small plateau, the main weakness being that it was overlooked from higher up to the west.<br/><br/>The site of the first gun was without question, a tactically perfect position in between two low rocks that gave out onto a long glacis sloping down east and towards the vehicle gate below us. I carried one drum and lay it down between the two rocks, cracking the catches open and setting up the sentry so it was in defilade between them but had a superb field of fire down the glacis for more than 400 metres across a forty-five degree arc. I plugged in the network devices, flipped open the control handset and powered up, leaving the gun in test mode until I had the second online.<br/><br/>We still had 270 degrees of perimeter to cover but south, the way we had come was the least likely direction of an enemy attack. The western quadrant was the next statistically least likely since it was away from the colony and any hostiles up there had already thrown away their best chance to engage us favourably during our advance. I therefore selected a location facing north along the ridge and parallel with the colony's western-most wall below us. This second gun had a less ideal site but it was still good, covering 250 metres of slope over a 40 degree arc. Some rocky outcrops provided cover for an enemy approach however.<br/><br/>I retired to the lee of the biggest rock on the west side to set up both guns control consoles, small black flip-top keypads with liquid crystal screens. I built a makeshift desk from the two carry drums, propping the lid of the upper one open with its pneumatic stay. The control desk was protected from the worst of the weather. I selected soft targets and visible wavelength auto-targeting before setting both guns to 'armed'.<br/><br/>I left the spare 1500 rounds of ammunition adjacent to each gun in the best covered location our small perimeter provided.<br/><br/>There are IFF tracking panels sewn into the waistbands of standard Marine combat pants as well as on the waist panels of the standard armour such as the Ape Suit and the KPBA. These tags are interrogated by the UC571-A's laser designator: the guns will not fire on friendly targets. I had IFF tags sewn into the waist band of both my long coat and my coveralls. According to my database the resourceful lab personnel had run countless tests on blast waves against test dummies wearing a variety of USCM combat clothing and it had transpired that in 88% of cases it was the waist area of the combat pants that was most resistant to being torn from a body during a blast. Helmets, boots, weapons and light armour panels such as greaves on limbs were dispersed early in the tests when subjected to lower pressure blasts. Jackets and pants legs and finally combat vests were more resistant although by the stages the average vest was blasted from the torso the human within it would have only a 2.7% chance of remaining combat effective.<br/><br/>Therefore the powers that make the decisions had put the tags into the marines waistbands.<br/><br/>Taking my pulse rifle I returned to scanning the westward perimeter again. I was becoming familiar with that skyline now. Following the Sergeant's order I powered up my internal motion tracker but it returned mostly a foggy mush out to it's maximum range. As I waited, ignoring the rain that plastered down my hair and ingressed down my upturned collar, I considered tactical situations where Bravo Team might have to retire onto our base of operations and through the sentry guns field of fire with a force of hostiles in close pursuit. That would be an enlightening test of the IFF system.