Flashcards would be great for summarizing key chapters, and are a really good way of condensing your knowledge down so you're learning the important parts (they helped me a lot through GCSE, and they're also easier to read over whenever you have the time)
Mind maps are better if you want to make links between topics, but I think flashcards would be a better way to revise because it's easy to lose track of where you are with mind maps, especially with a topic like history