What are some of the most desperate and bleak fights in anime?

The Saiyan Saga in DBZ before Goku shows back up is one of my favorites for this reason. The Z Warriors are completely outclassed and Nappa just slowly tears through basically everyone. Despite giving it their all, it really felt like they had no chance of winning.

What are some other battles in anime that felt bleak and desperate? Where someone is just outclassed