daelyte wrote: These would not prevent the enemy from using planetary bombardment from high orbit or beyond. All it would do is prevent them from using more surgical strikes, and make it difficult for them to invade.
In most cases time favors the defender. If you can slow the enemy down long enough for reinforcements or a relief fleet to make it to you then you have effectively defeated the invasion. I imagine both The Loroi and Umiak have many strong fleet formations hanging around for just such operations.
In past battles. Normandy, and Gallipoli there was a strong division in results. In Gallipoli the invasion force picked a bad location to begin with lacked proper resources, equipment,training and tactics. The second attempt to land troops behind the defenders failed due to the local commanders not moving quickly to exploit their temporary advantage and allowed the enemy to move into advantageous locations..the result was another bloodbath.
At Normandy, the invaders faced extremely well designed defenses, and fairly substantial opposition. However this time the defender hesitated due to disinformation and generally poor command structure resulting in the invaders succeeding in establishing a beach head...at high cost.
And once again at Inchon the invaders moved quickly and decisively taking advantage of several factors including the fact that all military doctrine said a landing there was too risky.
Had local defenders at Inchon and Normandy been reinforced, landing operations disrupted...As the case at Guadalcanal, the tide of battle would have quickly turned in favor of the defenders. Without ressuply, pinned down under heavy ground bombardment, and casualties rates that increase with every day your in a bad position. the invader will have to pull out and regroup.
as for orbital bombardment. It's been pretty well demonstrated that heavy bombardment alone cant break a populations will to fight. and can only disrupt not destroy a country, or planets ability to maintain it's war machine.
Air campaigns against Germany and Japan, nearly obliterated entire cities, There were more casualties in Dresden, and Tokyo Than in Hiroshima and Nagasaki . But both nations were able to fiercely resist landings up to the very end of the war.
If there was an outside force, available to assault and relieve a planet under heavy assault it's unlikely that the enemy could simply park itself in orbit and drop bombs, missiles, rocks on the planet at leisure. Sooner, more likely than later a relief force will show up and then the ships involved int he surface assault will have to pull back to avoid destruction or engage the relief forces.
So long story short.... too late
even if the defense isn't perfect, and relies on limiting and slowing down the enemy rather than defeating it completely You still have a pretty good chance of resisting an invasion.