Which blood cells are responsible for fighting infections?

White blood cells

Which bird is famous for completing dives that exceed speeds of 240 mph (386 km/h) when hunting prey? In chess, what is it called when you achieve victory in just two moves? Who lives across the street whom the Friends often spy on? Who initiated the 1864 "March to the Sea" during the Civil War? Who holds the record for most RBIs in one MLB season?