seizing control of the country; unifying the realm
Often used in historical contexts referring to the Sengoku period ambition to rule all of Japan. Can also be used figuratively for dominating a field.
Oda Nobunaga aimed to seize control of the country.
He is aiming to dominate the industry.
Compound of 天下 (てんか, 'the whole country, the realm') and 取り (とり, 'taking, seizing'), the nominalized form of 取る (とる, 'to take').