Nineteenth-century penal leaders supported suppressing prisoners’ communications within prisons and with family and friends. This idea was put into practice in prisons across the world.

• A prison in Warsaw, Poland, finished in 1835, was designed to suppress prisoners’ communication.^
• By 1869, the ordinary regime of imprisonment in Germany was described as solitary confinement.^
• Belgian prisons began suppressing prisoners communications in 1835.^
• Pentonville Prison, which began operation in England in 1842, was called the Model Prison. It strictly suppressed prisoners communications. Pentonville Prison attracted worldwide attention:
  

  In 1842 the King of Prussia, Frederick William IV, paid a visit to the Model Prison with his architect Busse. He was followed shortly by the King of Saxony, Grand Duke Michael of Russia, Prince Alexander of the Netherlands, and commissioners from the governments of France, Prussia, Austria, Holland, Denmark, Sweden, and lesser principalities and states. ^

• Hundreds of other prisons around the world later in the nineteenth century suppressed prisoners’ communication.^ ^ The Eastern State Penitentiary historical site observes:
  

  During the century following Eastern’s construction, more than 300 prisons in South America, Europe, Russia, China, Japan, and across the British Empire were based on its plan.