The way I now see this working is that the aggressor has to make several attacks at a Territory before they can break another’s control there. This gives the defender a chance to disrupt the invading force or its supporting population in the adjacent territory with counter-attacks. I’m sorry if this is getting repetitive, but there are differences from previous invasion proposals.

Change this line in the Transportation rule:-

If the target Territory is controlled by another Country, it cannot be moved to.

To:-

If the target Territory is controlled by another Country, this is called Invasion Transportation (or simply Invasion). Invasion lasts an indefinite number of periods (use ‘?’ to represent the number of periods in the “In Transit” section). In order to make an attack post at a Territory controlled by another Country, a Country must have a population presence in an adjacent Territory of at least the same amount as the number of units being moved in the Invasion, and must pay for a period of Invasion Transportation there, which costs the same as Hostile Transportation. If the defending Country loses control of the Territory, the attacker may reduce the number of periods of that Invasion Transportation to 0 and thereby complete the Invasion.

Add this before the list of attack methods:-

If a Territory is the target of an Invasion, the population being moved in the Invasion Transportation is considered the presence of their controlling Country in that Territory for the purposes of attack posts made by either the invading Country or the controller of the Territory. However the invader does not get the benefit of any Constructions in that Territory. If that presence is reduced to zero, the Transportation entry is removed.

Add this attack method:-

A Country performing an Invasion may use the Attack Method Invade if eir 2 immediately previous attack posts were against the same Country at that same Territory. The defending Country then loses control of the Territory and it becomes disputed.

In Construction, Change the first bulleted effect of Fortification to:

The effective size of an attacking presence in a Territory in which the defender has a Fortification is halved, rounding up, when calculating the results of its attack.

And also change the second sentence of the first bulleted effect of Cannon to:-

If e does, the effective size of the attacking presence will be multiplied by 0.75 and rounded up instead of being halved, when calculating the results of its attack.