The phone call came at around 4.20pm on Saturday. A bomb had been dropped on the house at our small farm in northern Gaza. My father was walking from the gate to the farmhouse at the time. It was our beloved place, that farm and its two-storey white house with a red roof. Nestled in a flat fertile agricultural plain north-west of Beit Lahiya, it had lemon groves, orange and apricot trees and we had recently acquired 60 dairy cows.

It was the closest farm to the northern border with Israel. Ironically, we always thought the biggest danger there was not from Israeli troops, who usually went straight past if they were mounting an incursion, but from stray Hamas rockets aimed at the Israeli towns north of us.

But shortly before sunset on Saturday, as Israeli ground troops and tanks invaded Gaza in the name of shutting down Hamas rocket sites, the peace of that place was shattered and my father's life extinguished at the age of 48. Warplanes and helicopters had swept in, bombing and firing to open up the space for the tanks and ground forces that would follow in the darkness. It was one of those F16 airstrikes that killed my father.

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The house was reduced to little more than powder, and of Dad there was nothing much left either. "Just a pile of flesh," my uncle, who found him in the rubble, said later with brutal honesty.

Like most Gazans, my mother, my sisters and my wife – who is nine months' pregnant – and I have spent the past week of the Israeli onslaught trapped inside our flat in the city. But my father had decided to stay up at the farm; he knew it would be impossible to get back to tend the livestock if the expected troop invasion began. But he called us every day.

The last time I saw him was on Thursday when he brought cash and a bag of flour. We talked about the imminent birth of my first child and how we would get my wife, Alaa, to hospital amid the bombing and chaos. Of course, on Saturday evening there was no hope of getting an ambulance up to the farm because the roads were cut off by the Israelis. So my uncle and brother drove the 8km and the rest of us sat, in shock, shivering in the dark apartment, bed covers over us to keep warm, the sound of non-stop tank shelling around us. Deep down we all knew Dad was dead. He would have been in or near the house, and if an F16 strikes directly at your house you know what it means.

They arrived to find a smoking pile of rubble. Most of the cows lay dead; others had run off injured. Mahmoud, a teenage relative, was with my father when the Israeli bomb smashed into the house. The force of the airstrike threw him 300 metres. They found Mahmoud's body in a neighbour's field.

We buried my father and Mahmoud yesterday morning in a very quick funeral, knowing Israeli tanks were just 3km away, on the outskirts of the city. We could hear the rattle of the machine-gun fire accompanying the tanks. The Israelis may say there were militants in the area of our farm, but I'll never believe it. The most advanced point for rocket-launchers is 6km south. Up at the border, it is just open farmland with nowhere to hide.

My father, Akrem al-Ghoul, was no militant. Born in Gaza and educated in Egypt, he was a lawyer and a judge who worked for the Palestinian Authority. After Hamas took over, he quit and turned to agriculture. Dad's father, Fares, who had been driven out of his home in what is now Israeli Ashkelon in 1948, had bought the land in the 1960s.

During the second intifada and until the Israelis withdrew from Gaza in 2005, the farm was taken over by Israeli settlers, but after 2005 we went there every holiday. In Gaza, the only escape is the beach or, if you are lucky enough, the farmland. My father hated what Hamas was doing to Gaza's legal system, introducing Islamist justice, and he completely opposed violence. He would have worked hard for a just settlement with Israel and a better future for Palestinians. When the PA gained control over the West Bank, he moved to Ramallah to help establish the courts there.

My grief carries no desire for revenge, which I know to be always in vain. But, in truth, as a grieving son, I am finding it hard to distinguish between what the Israelis call terrorists and the Israeli pilots and tank crews who are invading Gaza. What is the difference between the pilot who blew my father to pieces and the militant who fires a small rocket? I have no answers but, just as I am to become a father, I have lost my father.