‘And it came about in the fourteenth year of king Hezekiah, that Sennacherib, king of Assyria, came up against all the fenced cities of Judah, and took them.'
Compare for this Isaiah 36: 2 Kings 18:13 where the verse precedes the description of the surrender of Hezekiah and the paying of tribute mentioned above. This would strongly support the idea that the actual siege of Jerusalem followed closely on that affair. But it may be that the authors of Kings had Isaiah's scroll before them and simply inserted Isaiah 36:14-16 as a parenthesis.
‘The fourteenth year of king Hezekiah.' This was in 701 BC, which appears to conflict with 2 Kings 18:1; 2 Kings 18:9 which would make this the twenty eighth year of Hezekiah's reign. The probable explanation for this is that 729/8 BC was when Hezekiah began to reign as co-regent with his father, his father dying around 715 BC. Co-regency was favoured by the kings of Judah as it ensured a secure succession, the successor thus already being in a position of authority and recognised as the heir. This then assured the preservation of the line of David.
Sennacherib records this in his annals as follows: ‘But as for Hezekiah the Judean, who did not bow in submission to my yoke, forty six of his strong-walled towns and innumerable smaller villages in their neighbourhood I besieged and conquered, by stamping down earth-ramps and then by bringing up battering rams, by the assault of foot soldiers, by breaches, tunnelling and sapper operations. --- he I shut up like a caged bird within Jerusalem, his royal city. I put watch-posts strictly around it, and turned back to his harm any who went out of its city-gate.'
Archaeology bears testimony to the strong fortifications of cities of Judah at this time. Sennacherib thus had to engage in a drawn out campaign, and was clearly proud of his achievement. Note that he only mentions a watching brief on Jerusalem, a process of slow starvation. The larger part of his army was busy elsewhere. The tough fighting for Jerusalem itself was intended to take place later when everywhere else had been subdued.