Proud mothers and fathers would have been invited to the parade, where the salute was to be taken by Major-General Tawfiq Jaber, the commander of the police force in the Gaza Strip, which has been controlled by the militant Islamist movement, Hamas, since June 2007.
What nobody on the ground knew was that, just as the band played and the cadets formed up to march past Gen Jaber, they were in the cross-hairs of the Israeli air force.
It is not yet known if the gathering was hit by a guided missile or, as is more likely, a laser-guided bomb. What is certain is that a huge explosion ripped through the scene, killing at least 40 people, including the General.
Within minutes fifty sites, all Hamas police and security force facilities located from Rafah in the south to Gaza City in the north, were attacked by 60 jet fighters. Saturday is a normal working day in Gaza and all these buildings were occupied.
Plumes of thick black smoke rose into the grey winter sky the length and breadth of the Strip as the first wave of Israeli air strikes took place.
F-16 jets were heard overhead, along with the clatter of helicopter gunships and the whine of engines from unmanned drones.
At ground level, the air was filled the sound of ambulance sirens and the wailing of relatives gathered at Gaza’s numerous mortuaries, places that have seen plenty of carnage-fuelled grief over the years.
Once the smoke and dust cleared at the police headquarters, rescuers gingerly began searching the scene for signs of life. There were few.
Most of the fatalities appeared to be in uniform, although it is probable civilians were killed in the police compound.
With Israel restricting the entry of foreign reporters to Gaza, authoritative accounts of what happened came from local sources. The Telegraph’s fixer in Gaza went into mourning after losing a cousin in the attack.
A local television cameraman filmed uniformed bodies piled up on top of each other as all around the wounded writhed in pain.
Rescuers carried those showing signs of life to cars and ambulances, while others tried to revive the unconscious. Several of the rescuers beat their heads and shouted: "Allahu akbar (God is greatest)." One badly wounded, prostrate man quietly recited verses from the Koran.
Islam Shahwan, the Hamas police spokesman, gave the death toll at the police headquarters as at least forty. This was the most prominent target of Israel’s most punishing assault on the Gaza Strip since the end of the Second Intifada in 2004.
The Israeli government gave the green light for the military operation at a meeting of the National Security Cabinet on Christmas Day. The NSC met to deliberate how to deal with the expiry of a six-month ceasefire between Israel and Hamas on Dec 19.
Hopes for a renewal of the truce had been scuppered by tit-for-tat exchanges that began when Israeli ground forces raided Gaza in November. Their aim was to close down a tunnel linking Gaza with neighbouring Egypt. Militants were preparing to use this to smuggle in rockets to launch at southern Israel.
That ground operation, during which three Palestinian fighters were killed, sealed the fate of the ceasefire. The militants began to fire rockets in large numbers at the towns of southern Israel for the first time in months, placing commanders under immediate pressure to respond.
Israel will hold a general election in February and politicians cannot appear anything but robust in dealing with the threat posed by rocket fire from Gaza.
After the NSC’s decision to authorise a military operation, the only question was what kind of attack would follow. Israel has used ground forces before, but this has never provided a lasting solution to the menace of the rockets launched from Gaza.
This time, Tzipi Livni, the foreign minister, Ehud Barak, the defence minister, and other security chiefs decided on something quite different.
Instead of a ground offensive or pinprick air attacks, they would order a massive air assault on all known Hamas security targets. Hamas operatives did not fire all the rockets launched from Gaza - other militant groups such as the Islamic Jihad Party fired many. But Israel believes that Hamas, as the governing power in Gaza, could be held responsible and targeted accordingly.
The office of Ehud Olmert, Israel’s outgoing prime minister, issued a statement explaining that the "cabinet has tasked the prime minister, foreign minister and defense minister with deciding on the time and manner of the said action". this added: "Following a unanimous decision, the three have decided on the Israeli Air Force strike which took place this morning. Israel stresses that it will continue to take action against the terror attacks and rocket fire emanating form Gaza against Israeli citizens.’’
After the first round of air attacks, the Israeli air force sent up patrols to deal with the predicted wave of retaliatory rocket launches.
After the initial round of strikes, sources inside Gaza reported more explosions as the air force sought to destroy rocket-launching parties.
However, they failed to stop all the retaliation. Late in the morning, an Israeli man was killed by a rocket in the Israeli town of Netivot. He was the first Israeli to die as a result of Palestinian rocket attacks since June.
In total, nine Israelis have been killed by rockets launched from Gaza since 2005, when it withdrew from the territory and dismantled all settlements.
Yesterday alone saw over 200 Palestinian deaths.