Painting Mona Lisa. Jeanne Kalogridis

Lorenzo was nearby made him push, with arms and legs, against the quiet water. With a final, painful burst, he reached the sunken branches and pressed a palm against the slick surface of the trunk.

      At once, he grew remarkably dizzy, and heard a rushing in his ears; he shut his eyes and opened his mouth, gasping for air. There was none to be had, and so he drank in the foul Arno. He retched it up at once, then reflex forced him to gulp in more.

      Giuliano was drowning.

      Though a child, he understood clearly that he was dying. The realization prompted him to open his eyes, to capture a last glimpse of earth that he might take with him to Heaven.

      At that instant, a cloud moved overhead, permitting a shaft of sunlight to pierce the river, so thoroughly that it caused the silt suspended in the water to glitter, and illumined the area directly before Giuliano’s eyes.

      Staring back at him, an arm’s length away, was the drowning Lorenzo. His tunic and mantle had been caught on an errant branch, and he had twisted himself about in a mad effort to be free.

      Both brothers should have died then. But Giuliano had prayed, with a child’s guilelessness: God, let me save my brother.

      Impossibly, he had pulled the tangled clothing loose from the branch.

      Impossibly, the freed Lorenzo had seized Giuliano’s hands, and pulled the two of them up to the surface.

      From there, Giuliano’s memory became more blurred. He only remembered snippets: of himself vomiting on the grassy shore while the slave woman pounded his back, of Lorenzo wet and shivering, wrapped in picnic linens; of voices calling out: Brother, speak to me! Of Lorenzo in the carriage on the ride home, furious, fighting tears: Don’t ever risk yourself for me! You almost died! Father would never forgive me …! But the unspoken message was louder: Lorenzo would never forgive himself.

      In the cathedral of Santa Maria del Fiore, Bernardo Bandini Baroncelli lifted his knife to deal Giuliano another blow.

      Dear God, Giuliano prayed, with the sincerity of a child. Let me rescue my brother.

      With strength he did not have, he then pushed backwards against his first attacker, causing the man to step onto the hem of his garment and fall, tangled in his robes.

      Time slowed then for Giuliano, just as it had that day in the Arno. Despite his lethargy, he willed himself to do the impossible and create a barrier between the attackers and Lorenzo. If he was unable to cry out a warning to his brother, he could at least slow the murderers down.

      Then he heard Lorenzo’s voice. Giuliano! Brother, speak to me! He could not have said whether it came from within the Duomo, or whether he heard an echo from childhood, the voice of an eleven-year-old boy calling from the banks of a river. He wanted to tell his brother to run, but he could not speak. Struggling to draw a breath, he choked on warm liquid.

      Baroncelli tried to edge by him; but Giuliano stumbled intentionally into his path. Francesco de’ Pazzi pushed past them both, the sight of blood stirring him into a frenzy; his small black eyes sparkled as his wiry body shook with hatred. Raising his dagger – a long blade, almost as slender and keen as a stiletto – he too, tried to move beyond Baroncelli’s victim, but Giuliano would not let him pass.

      Giuliano opened his mouth to an anguished wheeze, meaning to scream instead, You will never get near my brother. I will die first, but you will never lay a hand on Lorenzo.

      Francesco simply snarled something unintelligible and moved to strike the young man.

      Weaponless, Giuliano raised a defensive hand and the knife pierced his palm and forearm; but compared to the agony in his chest and in his back, these fresh wounds were no worse than the sting of an insect. Taking a step towards Francesco, towards Baroncelli, he forced them backwards, and gave Lorenzo time to flee.

      Francesco, a vicious little man, let loose a torrent of all the rage, all the enmity that his family felt towards the Medici. Each phrase he uttered was punctuated by a further blow of his dagger.

      ‘Sons of whores, all of you! Your father betrayed my father’s trust …’

      Giuliano felt a deep, piercing bite in his shoulder, then in his upper arm. He could not keep it raised, so he let it fall, limply, to his blood-soaked side.

      ‘Your brother has done everything possible to keep us out of the Signoria.’

      Harsher wounds were dealt now upon Giuliano’s chest, his neck, followed by a dozen blows to his torso. Francesco was a madman. His hand and blade pummelled Giuliano so swiftly that the two were enveloped in crimson spray. His movements were so wild and careless, he even pierced his own thigh, shrieking loudly as his blood mingled with his enemy’s. Pain fuelled Francesco’s fury as he continued to strike.

       Spoken ill of us to His Holiness.

       Insulted our family.

       Stolen the city.

      Such calumny against his brother should have incited Giuliano’s anger, but he had found a place where his emotions were still.

      The waters inside the cathedral were murky with blood; he could barely see the wavering images of his attackers against the backdrop of scrambling bodies. Baroncelli and Francesco were shouting. Giuliano saw their mouths agape. The glint of wielded steel was dulled by the muddy Arno, and he could hear nothing. In the river, all was silent.

      A shaft of sunlight streamed in from the open door leading north to the Via de’ Servi. Giuliano stepped towards it, intent on looking for Lorenzo, but the current pulled strongly on him, and it was hard to walk through the swirling water.

      Just beyond his reach, the raven-haired Anna wept and wrung her hands, mourning the children they might have had; her love tugs at him. But it is Lorenzo who has the final hold on his heart. Lorenzo, whose heart will break when he finds his younger sibling. It is Giuliano’s greatest regret.

      ‘Brother.’ Giuliano’s lips merely formed the word as he sank to his knees.

      Lorenzo sits on the banks of the Arno, clutching a blanket round his shoulders. He is soaked through and shivering, but he is alive.

      Relieved, Giuliano lets go of a shallow sigh – all the air that remains in his lungs – then sinks to where the waters are deepest and black.

       VIII

       26 April 1478

       To the Priors of Milan

       My most illustrious lords,

       My brother Giuliano has been murdered and my government is in the gravest danger. It is now time, my lords, to aid your servant Lorenzo. Send as many soldiers as you can with all speed so that they will be the shield and safety of my state, as always.

       Your servant

       Lorenzo de’ Medici

December 28, 1478

       IX

      Bernardo Baroncelli rode kneeling in a small horse-drawn cart to his doom.

      Before him, in the vast Piazza della Signoria, loomed the great, implacable Palazzo, the seat of Florence’s government and the heart of her justice. Topped by battlements, the fortress was an imposing, almost windowless rectangle, with a slender campanile tower at one corner. Only an hour before he was led to the cart, Baroncelli had heard its bell tolling, low and dolorous, summoning witnesses to the spectacle.

      In the morning gloom, the Palazzo’s pale stone façade appeared grey against the darkening clouds. Before the building, rising out of a colourful