But Sinwar was unique in his ability to understand and torment the Israeli psyche. He spent years in jail studying the ways of his captors and becoming fluent in their language. He knew that to beat your enemy you must know them first.

He understood that Israel could be lulled into a false sense of security. Under his command, Israelis were deceived into thinking Hamas wanted a period of calm, while in reality it was preparing for the biggest attack in either sides' history.

He also knew Israeli society was hugely divided and exploited that weakness. The most extreme government in Israeli history under Benjamin Netanyahu was polarising the country like never before, pushing deeply controversial plans for reform.

And he realised that a diplomatic détente between Israel and former Arab enemies in the gulf and ultimately Saudi Arabia, threatened to marginalise the Palestinian cause.

According to internal Hamas documents reportedly leaked recently, Sinwar brought forward the attack plan he had devised. It would unleash a devastating assault on Israeli communities outside Gaza.

But it would not, as he had hoped, be joined in full force by Israel's other enemies, Hezbollah to the north and Iran. Their support would be more qualified.

For more than a year, Israel's military response to 7 October has failed to achieve its war objectives. It has not secured the release of all Israeli hostages. It has not destroyed Hamas and it had not decapitated its leadership – until now.

Sinwar eluded Israeli efforts to kill him, apparently hiding in the labyrinth of tunnels Hamas dug under Gaza. While lieutenants were taken out one by one, Israel's ultimate prize remained at large.

He is now dead and that is a huge loss to Hamas.

Read more:
Israeli strike 'kills 28 including children'
Who is Hamas leader Yahya Sinwar?

Sinwar was without doubt a masterful strategist, a fanatical believer in his cause and also ruthlessly brutal.

He was said to have killed suspected Palestinian collaborators with his bare hands and tortured others. He seemed to believe no method was beyond the pale if it furthered a cause he professed was sacred.

Israel has now removed one of its biggest and most capable enemies.

Taking Sinwar's scalp gives Israelis the opportunity to start ending their war in Gaza, having fulfilled one of its primary aims. It is unlikely to do so immediately but Sinwar's demise almost certainly brings forward that day.

Israel will come under huge pressure now from America and others to seize the moment, do a deal to bring home the hostages and wind up this war.

Sinwar's death raises new questions

By Alistair Bunkall, Middle East correspondent, in Jerusalem

The killing of Yahya Sinwar has settled a score for Israel and delivered some justice to Israelis, but it has also raised many questions about the future of the war and Hamas as an organisation.

Here are some of them:

• Sinwar will be replaced, but by who? Most of Hamas's senior leadership in Gaza have already been eliminated. The obvious successor would probably be his brother, Mohammed Sinwar, if he is still alive. But he doesn't have the authority or following of his brother, so can he, or another leader, hold the group together?

• What does this mean for the remaining hostages? Sinwar was the point man for Hamas in Gaza - until his successor is appointed, it's not clear who the negotiators can deal with.

• Did Sinwar leave instructions for handling the hostages in the event of his death? Will Hamas seek revenge against them for the killing of their leader?

• How crucial was Sinwar's role in co-ordinating Hamas in recent months? The group was already quite fragmented and had become more so in recent months. To what extent did he retain tactical day-to-day leadership or was he a figurehead in hiding and on the run?

• Will remaining Hamas fighters be inspired by his death to keep fighting Israel, or will some of the more moderate members see it as an opportunity to step back?

• Where does this leave Hamas leadership abroad, in Qatar and Turkey? What influence do they retain and do they have any remaining influence over the organisation in Gaza?

The answer to some or all of the questions will have a significant bearing on the future course of the war.