From our Correspondent in the Front Line. Lake Victoria.

How can our navy attack the Swarm? We all know that the Sa'arm avoid water and mostly stay in their tunnels. What can a lake-bound naval force do to help resist the invaders? As Vice-Admiral Kolekile, commander of the African Union's Lake Victoria Naval Assault Force explains, "Since the Swarm will not come to the water we have to take the water to the Swarm.

"In the years before the Swarm landed humanity prepared a number of underwater bases that would be relatively immune to the Swarm. Since Africa was considered to be a likely target for a Swarm invasion one of those bases was set up here in Lake Victoria so that our forces would have secure areas nearby to rest and recuperate between attacks. At first the LVNAF just provided support for our brave ground forces but then one of our Petty Officers had an idea."

The now Chief Petty Officer Julia Ssetongo is a petite brunette with a trim figure and bright eyes. She appears harmless; not the kind of woman you would think responsible for the deaths of tens of thousands of lizards. As she says, "It was mostly luck. I just happened to be in the right place at the right time. I was assigned to help one of our geophysics teams map the Sa'arm tunnels around the lake so our infantry could plan their attacks. Normally I don't get to see their maps -- they are for the army planning people -- but in this case I did. I noticed something about one of the Sa'arm communications tunnels."

The geophysics teams do not actually go anywhere near the tunnels of course. As they explained to me they use techniques from the oil industry, enhanced with Confederacy assistance, to find underground structures by working from the surface. Julia was on a small ship moving the geophysics team round the lake's shore as they did their survey and marked up their maps.

As Julia tells it, "On such a small ship we were all pushed in close together, so I saw some of the tunnel maps laid out on the mess table. I noticed a shallow communications tunnel that came pretty close to the lake, closer than any other tunnel. The army people weren't very interested in it but it struck me that there was a different way, a navy way, we could attack it."

In my talks with the army planning staff it became clear why they usually ignore Swarm communications tunnels. They are long tunnels joining one infestation to a second hive some distance away. They have no branches and no exits to the surface. The Sa'arm could easily seal off any army incursion and dig an alternative route. It is far more effective for the army to directly attack one of the hives at the ends of the tunnel rather than in its middle. They were quite happy to let the navy have a crack at Julia's tunnel.

Julia passed her idea upwards to where it reached the Vice-Admiral -- a big, solid looking man, almost the size of a Confederacy Marine. He had a glint in his eye, "I leapt at it. Here was a way for the navy to attack the Swarm directly, instead of simply acting as backup to the army. Great for morale. I put my planning people on it and we soon had logistics working all hours getting together the equipment we wanted. They did a superb job, I must say. We suddenly needed a whole lot of stuff that had not been required before and they had it all there for us when we needed it."

Julia is becomingly modest about her achievement. "I just had the initial idea. It took a lot of hard work by other people to make it into a workable plan. My initial thought would just have been a one-off attack. It was all the others who built it into the campaign it has become."

And indeed Julia's idea has become a full campaign. To see how it was progressing I boarded a submarine for a journey out over the lake bottom. Through a porthole I could see the entrance to a water-filled tunnel sloping down into the bed of the lake. The tunnel was narrow, but the helmsman assured me that the automatics would keep us from crashing into the sides. Most reassuring! As we descended he explained, "This is our first tunnel that we dug down towards the Swarm tunnel." He also pointed out various side tunnels where the Swarm tried to stop us and where we dug back towards them. "At the end is a T-junction where we broke into their original tunnel and flooded it. You will have to disembark there because this sub is too long to turn the corner. We have a small base at the junction, with other subs that work along the length of the Swarm tunnels that we have captured."

In that underground base I talked to Leading Seaman Ibrahim Magwaza, one of the team who are pressing forward with the attack on the Sa'arm. "Once we broke into the Swarm's communication tunnel they quickly sealed things off at both sides, just as we expected. It wasn't as if our arrival was a surprise to them. When the initial rush of water had subsided we did two things. First we set up some pressure doors here at the T-junction to protect ourselves. Second we sent down two men with scuba-scooters and waterproof demolition charges, a bit like the one-man torpedoes used in World War Two. They laid their charges at the Swarm's two new bulkheads and withdrew quickly behind our pressure doors. That made short work of those Sa'arm barricades. We opened our doors and let in more water to fully flood the newly exposed sections of Swarm tunnel. It was a real mess down there. We caught both their digging crews working on a bypass tunnel from each end."

Of course the campaign is now a lot more sophisticated than in those early days. The captured tunnels are well supplied with listening devices to both locate Sa'arm counter-mining and to help geophysics study the layout of Sa'arm tunnels and what barriers they have placed in our way. The uphill end of the tunnel is relatively quiet now because it is not close enough to the hive at that end to make the effort worthwhile. The downhill end is a different story. The naval campaign has actually reached inside the enemy hive and is continuing its advance.

The history of the campaign, as related by the naval planning team, is fascinating. In the early days they were still learning, and used a lot of stopgap and experimental techniques. The manned scuba-scooters were quickly replaced by remotely controlled mini-subs. As they advanced further into Sa'arm territory it was taking too long for the crew to get back to safety. Using disposable unmanned mini-subs halved the time needed to place the explosives. The explosives themselves were also getting more sophisticated. Initially the demolition charges were replaced by larger depth charges as the Swarm thickened their bulkheads. However, as the Sa'arm began to use more sophisticated bulkheads to seal off their tunnels so we had to use more sophisticated means of attack. "My favourite was the 'Ring of Death'," explains Lieutenant Jacob Magwaza. "The Sa'arm had started armour plating the front face of their bulkheads so we switched to using shaped charges to penetrate their armour. A single shaped charge just punches a single hole, but the 'Ring of Death' was made in a ring so it cut around a disc in the middle of their bulkhead. Water pressure then punched out the central piece and we got a much much larger hole. That put a lot of water through into their side very quickly and did them a lot of damage. After a bit they reacted by putting up a second bulkhead behind the first, so we made our rings in two sizes. We used a full size ring to blast a two metre hole in the first bulkhead and then quickly brought up a smaller 1.75 metre ring to smash through their second bulkhead. The lizards didn't like that one bit."

The Sa'arm may not be original thinkers, but they are good at remembering things that have been useful to them in the past. Their bulkheads now use spaced armour in order to defeat shaped charges. Nevertheless our naval teams have overcome this as well. "It is not as if we haven't seen spaced armour on Earth for years -- even before the Confederacy arrived," as the Lieutenant explained. "Besides, we can always go around via the surrounding rock rather than straight through the bulkhead itself."

The first stage of the campaign just worked down the Sa'arm tunnel towards the hive at the eastern end. Once the boundary of the hive was crossed there were a lot more directions available for attack and a lot more opportunities to hurt the Sa'arm right in their own backyard. "Our biggest success so far has been flooding one of their large vertical shafts," the Vice-Admiral says proudly. "That single shaft has literally dozens of exits in different directions and at different levels. It gives us a central position from which to attack them and many different options as to where we strike next. That gives us the flexibility to be able to isolate parts of the hive complex, rather than just having to advance on a single front as we did initially. Now they don't know where we will attack next.

"We can tell that the shaft is important to them because it is the one place they have made any real effort to pump out the water. It shows how completely stupid they are when it comes to water. Once it gets above ground it just flows straight back into the lake so they are not doing themselves much good! We even got our air force to bomb the banks of the outflow and flood a minor exit to their hive that was close by. The Swarm just do not understand how to deal with water. That gives us in the navy a big advantage."

Vice-Admiral Kolekile heaped praise on his geophysics team. "They can now give us incredibly detailed maps of what the inside of the Swarm hive is like and also the design and placing of the bulkheads they have set up to hold back the water. We can also keep close track of their counter-mining and other measures so we can see how they are trying to stop us. That helps our planning team no end."

He also had a good word for the help he had had from the Confederacy. "I know that the Confederacy cannot give us all that they have -- some of it would be incredibly dangerous in the hands of the Swarm -- but they have been generous to a fault with stuff that will not help the enemy. The geophysics is a good example where their help with computer technology has been instrumental in the effectiveness of our data gathering and analysis. The Swarm do not seem to use computers much so we were helped with some useful Confederacy ideas. Our new computers are far advanced beyond what we had on Earth before the Confederacy contacted us, even though they are nothing much compared to a Confederacy AI. What seems advanced to us is thousands of years out of date to the Confederacy. So even if the Swarm do capture it and use it, it will not be a problem for the Confederacy to find a counter."

As well as using Confederacy technology we have also borrowed some techniques from the Sa'arm themselves. As the Vice-Admiral explained, "Whatever we might think of them, the Swarm are good at tunnelling so we need to match them at it. We have managed to adapt and improve some of the tricks that they use and turn those same tricks back against them. It has helped us both with our counter-mining and when we have to dig our way around a large obstruction."

The Vice-Admiral is well aware that this particular campaign cannot continue forever. "There is only so much water in the lake," he says ruefully. "Eventually the Swarm are going to come up with a way to drain it or it will run dry and we will have to move on." Surprisingly, he is less worried about the possibility of a Sa'arm nuclear strike on his base. "Why should I worry? The Swarm can drop a bomb on Cape Town or New York as easily as they can drop one here. When we started this we all knew that we might have to die to help defend Earth. Besides, such an attack would cause the mother of all pressure waves in the tunnels and flood a whole lot more of the Swarm hive. They would do themselves more damage that they would do to our forces. If we get any sort of warning then we have an evacuation plan which we practice regularly and keep up to date."

Our brave and resourceful navy is learning how to take the war, and the water, to the enemy and we can be sure that all that the Lake Victoria force has learned will continue to be put to good use. Already sailors from other navies: the US, the EU and the Chinese navies for instance, are being seconded to Lake Victoria to learn for themselves how a navy can fight the Sa'arm.

"The future?" the Vice-Admiral says, smiling, "Just remember that at some point the Swarm's tunnels are going to reach the sea."