1.
fierce battle, intense combat
A violent or intense military battle.
2.
close contest, fierce competition
A highly competitive contest where the outcome is uncertain, used for elections, sports, business competition, and other non-military contexts.
Usage
The figurative sense (close competition) is very common in modern Japanese, especially in news reporting about elections and sports. The expression 激戦区 (hotly contested district) is a standard political term.