This battle proved that defense with variable depth, and powerful reserve shock troops waiting for the counter attack
Basically make the enemy attack you, ie in your territory,
Don't concentrate defensive structures but spread them,
Have strong but stretched fortifications with defensive reserve in central positioned and not entrenched , so it can entrench at any point enemy threatens,
These forces and defences remove the shock or blitz from the enemy attack, bog or slow them over own territory which is mined , anti tank obstacles and AT teams,
Once the enemies shock or steam is slowed or ruined , and since attacks are concentrated to break your defence from a single point (ardennes example) , that means attacking forces concentrated too , and in enemy territory, and bogged down ( even if for a really short time )
A strong offensive reserve can now attack this force from any friendly direction, perform a pincer movement and surround it and what would follow would be a blood bath of trapped force.
Though in modern battles there are many more variables, yet this is the core defensive strategy for the 21st century , allowing smaller forces to thwart large attacks by using assymetric techniques ,
The only way to defeat this strategy is either overwhelming air superiority or
Attack before the enemy fortifications are ready
In indo Pak case, in Kashmir the strategy of strong of spread bunkers and observations posts, with a battalion reserve in a central position along with fire support company , so if any single lightly manned post ( although the fortifications are built to host a strong force ) or area is attacked , immediately battalion reserves can reach the place within in minutes if not then under an hour,
Also we can see army establishing strong reserve groups ie army reserve north and south , which is the same battalion concept I outlined but scaled up to divisions,
This perfect strategy was first effectively used in the kursk salient, although here the Russians knew the attack was coming and the Germans delayed it as well , allowing the red army to construct trenches which if layed out as a single road would stretch from Moscow to Berlin.
Personally this has been my favourite war documentary series