What is an action the first ruler of the qin dynasty took to control his empire?

  The action was to have a large and powerful army.

Explanation: The action taken by the first ruler of the Qin Dynasty was to have an army superior in number to those of other dynasties, in order to achieve the unification of China. Objective what he achieved, thanks to the conquest of most states and making the State of Qin a superpower and with an obviously powerful army.

answer; /// i believe the correct answer is (oasis)

the lachish letters were written by hoshaiah, a military officer stationed possibly in mareshah,   and sent to yaush, possibly the commanding officer at lachish.

the series of letters were written in carbon ink in ancient hebrew on clay ostraca, shortly before lachish fell to the babylonian army of king nebuchadnezzar in 588/6 bc during the reign of zedekiah, king of judah.