Shalmaneser V was king of Assyria during the reign of king Hoshea. Shalmaneser king of Assyria came to Israel to attack Hoshea. The reason he did this was that Hoshea was Shalmaneser's vassal and paid him tribute, but Hoshea stopped paying him this tribute. Hoshea was captured and put in prison for this by Shalmaneser.
The king of Assyria invaded the whole land and laid siege to Samaria, the capital of Israel, for 3 years. The Assyrians captured Samaria and sent the Israelites to Assyria. This happened because of Israel's sin against God. They were sent into exile because they rebelled against their Foundation: the LORD. This did not come without warning, many prophets warned Israel this would happen unless they repent. Israel, being a stiff-necked people, refused to listen to God's prophets. And then this disaster fell on them. The king of Assyria filled the empty cities of Israel with people from Babylon, Kuthah, Avva, Hamath and Sepharvaim. They did not worship the LORD, and were attacked by lions. One of the priests of God was sent to teach them to worship the LORD and be spared. They worshiped the LORD along with their own false gods.