CQRS versus Event Sourcing. When do you use both, or just one?

I've been checking out different ways to structure software lately, and CQRS and Event Sourcing keep coming up. They're often paired, which makes me wonder when you'd use them on their own instead of together. Like, what if your read model is tricky but you don't really need a whole event log for keeping track of history or auditing stuff. Could you just use CQRS then, without Event Sourcing? And on the flip side, are there times when Event Sourcing makes sense all by itself, without splitting commands and queries? I'd love to hear some actual stories or examples of when these patterns worked out well, or when they kinda crashed and burned.