Broadly speaking, there are two strategies in winning a war: "attrition" (starving the enemy into surrender) and "overwhelming" (defeating the enemy on the battlefield).

Both sides tried both strategies in the WW1, and, in the end, Entente won by attrition.

Moreover, the attempts at the battlefield victory were so costly, that the Western allies did not even consider it an option by the start of WW2.

Thus, the war plan included a rigid defence and a tight blockade, not a decisive offensive, public statements to the contrary notwithstanding.

Broadly speaking, there are two strategies in winning a war: "attrition" (starving the enemy into surrender) and "overwhelming" (defeating the enemy on the battlefield).

Both sides tried both strategies in the WW1, and, in the end, Entente won by attrition.

Moreover, the attempts at the battlefield victory were so costly, that the Western allies did not even consider it an option by the start of WW2.

Thus, the war plan included a rigid defense and a tight blockade, not a decisive offensive, public statements to the contrary notwithstanding.