How did the Battle of Shiloh change grants thinking about his military plans?

Mindful of the experience made at the battle of Shiloh, Grant never more neglected of making his battle line covered by field fortification.

Even during the attacking phases of a battle, the advancing units were ordered to entrench in the best possible way the ground they gradually would conquer, thus preventing them from being driven back by an enemy counterattack and from suffering excessive losses during the fighting.