So long as the opposing forces are at the outset approximately equal in numbers and moral and there are no flanks to turn, a long struggle for supremacy is inevitable.
Struggle Moral Flanks
Further, a defensive policy involves the loss of the initiative, with all the consequent disadvantages to the defender.
Consequent Initiative Loss
Once the mass of the defending infantry become possessed of low moral, the battle is as good as lost.
Battle Infantry Moral
The idea that a war can be won by standing on the defensive and waiting for the enemy to attack is a dangerous fallacy, which owes its inception to the desire to evade the price of victory.
Won Waiting War
Obviously, the greater the length of a war the higher is likely to be the number of casualties in it on either side.
Side War Casualties