Due to the heavily armed militaristic state of gavlend those attempts of invasion had failed very early. We have also shot down most of the bombers, which usually don't have a lot of fuel when they get to Gravlend. We also don't really use ports; we just dock the boats wherever. Also, we send a huge force of soldiers to the island to retake it. We also have counter batteries attack the naval boats, which has caused them to most likely retreat.