"I’m glad the GWOT era is coming to an end and hope we can learn from all the mistakes we made along the way" I'm curious about your thoughts on the subject

"I’m glad the GWOT era is coming to an end and hope we can learn from all the mistakes we made along the way" I'm curious about your thoughts on the subject - what do you consider mistakes? What do you think the lessons are? Are there books or other resources that you'd recommend?