For more than a decade, Israel’s military leadership grudgingly acknowledged one overriding trait in its Gaza enemy: Hamas knew how to bide its time.

“Let the beast sleep until you’re ready,” was the mantra of Mahmoud Ajrami, a veteran Palestinian fighter who has trained a generation of Gaza militants.

The examples were aplenty. In 2018, Hamas released images of Israeli soldiers in the crosshairs of its snipers — the shot never taken, even as the Israelis shot at protesters at the border fence. Another video showed militants destroying a military bus with a Kornet missile — but waiting for the soldiers to disembark and the driver to take a cigarette break.

The apparent restraint was interpreted by Israel as a sign that Hamas was deterred. But to Ajrami, the militant group was merely waiting to draw Israel into a battle at the time of its choosing.

“Bring the beast to me, and we will slay it together,” he vowed to fighters outside his palatial villa in 2021, after Hamas claimed victory over Israel in an 11-day war that involved a ferocious exchange of Palestinian rockets and Israeli air strikes — but no ground troops.

The trigger came on October 7, when Hamas fighters rampaged through Israeli towns and military posts, killing more than 1,400 people and taking 230 hostages, according to Israeli authorities — the biggest loss of life within the Jewish state since its creation. The scale and horrors of the attack have drawn Israel into its biggest ever military operation in Gaza, its air strikes and artillery flattening large parts of the territory with more than 8,000 people killed, according to Palestinian officials.

With technological superiority and massed weaponry on its side, Israel has now launched its first ground offensive in Gaza in almost a decade. Since late Friday a vanguard has moved with Merkava tanks into largely unpopulated areas to the north of the strip.

But within a few minutes’ drive lie the warrens of al-Shati and Jabalia refugee camps — and then, Gaza City, the heart of Hamas’s political and military machinery.

“As the IDF goes into Gaza, Hamas has the home advantage — and they’re ready,” cautioned Devorah Margolin, the Blumenstein-Rosenbloom senior fellow at the Washington Institute for Near East policy.

As recently as August, Major General Yitzhak Brik, a former military ombudsman, warned Israel was “not ready for war”. Its soldiers have not fought a major land battle since 2014 — the last time it deployed troops inside Gaza — and its top brass has been consumed by potential threats from Iran, rather than the territory right next door.

Meanwhile, Hamas had grown stronger militarily since 2008-09, when it first fought an Israeli ground assault, military officials and analysts said.

Even then, Hamas’s military wing, the al-Qassam Brigade, fielded 16,000 fighters alongside 2,000 dedicated combat troops. Now, according to the IDF, it has as many as 40,000 elite fighters, and an arsenal of drones and about 30,000 rockets. It has fired 8,500 since October 7, draining Israel’s Iron Dome interceptors to the point where the US had to fly in replacements.

Emile Hokayem, director of regional security at the International Institute for Strategic Studies in London, said Hamas had been trained by “the best in the business”, referring to Iran’s elite Revolutionary Guard and its most powerful proxy, Hizbollah in Lebanon. “It is also a learning organisation that has fought Israeli forces several times,” Hokayem said. “Hamas knows its terrain extremely well and will defend it fiercely and with ingenuity.”

Its fighters already showed during their October 7 assault that they could pull off a tightly co-ordinated operation that involved at least 1,500 troops attacking Israel from land, air and sea, under cover of a barrage of 3,000 rockets that nearly overwhelmed Israel’s Iron Dome system.

In Gaza, Hamas has dug a giant network of deep, bombproof tunnels, and stocked them with provisions to resist a months-long Israeli siege.

“We have been prepared for an [Israeli] ground offensive since before we even launched our attack,” Ali Barakeh, a senior member of Hamas’s exiled political leadership, told the Financial Times last week. “We have some surprises for the enemy,” he added. “We are able to face an urban war more easily than an air war — there’s no comparison.” A map and diagram of the Gaza Metro. Hamas' extensive network of tunnels has often been a problem for the IDF and is likely to hinder any ground offensive. As well as providing storage, command centre and transportation, tunnels into Israel have been used to mount attacks in 2004, 2006 and July-August 2014. Each tunnel can cost up to $3mn to build. So far Israel's foreign ministry claims 1,370 tunnels have been built since 2007.