I think the explanation lays in the strategic equilibrium: new Venice is small, but adding its contribution to one of the parties involved would resolve the war in favor of the alliance.

Let's explain this concept with some numbers, and assumptions:

• the side with higher score wins. Equal score cannot be decided
• the score of an alliance is given by the sum of the scores of the components

If A and B are superpowers, let's say they score 100 each, and are thus in equilibrium. Now the third small country C is just a feeble 3.

Any attempt to attack C, from either A or B, will result in C joining the other side and breaking the equilibrium. Since both A and B are aware of this situation, they respect the neutrality of C to prevent the country joining the other side.

Throwing away the shame of the international community, which in your case consists only of the enemy and the invaded country, I think the explanation lays in the strategic equilibrium: new Venice is small, but adding its contribution to one of the parties involved would resolve the war in favor of the alliance.

Let's explain this concept with some numbers, and assumptions:

• the side with higher score wins. Equal score cannot be decided
• the score of an alliance is given by the sum of the scores of the components

If A and B are superpowers, let's say they score 100 each, and are thus in equilibrium. Now the third small country C is just a feeble 3.

Any attempt to attack C, from either A or B, will result in C joining the other side and breaking the equilibrium. Since both A and B are aware of this situation, they respect the neutrality of C to prevent the country joining the other side.