Come learn 2000+ kanji and 6000+ vocabulary words with WaniKani.
Remember how 襲撃 is an assault or attack? This is the verb form, so it's to attack or to assault.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
Little did they know they would be able to attack titans by air.