The First Utrecht Civil War  took place between 1470 and 1474 when the Hook and Cod wars spilled over into the Bishopric of Utrecht. David of Burgundy, illegitimate son of Philip the Good, Duke of Burgundy had been  appointed as bishop of Utrecht in 1456 with support of the Cods. The Utrecht chapters, however, had elected the Hook-favoured provost Gijsbrecht van Brederode as bishop. But Philip the Good used force to make David's appointment be accepted. Nevertheless, opposition against his rule remained, and David of Burgundy even found it safer to leave the city of Utrecht and take up residence in Wijk bij Duurstede. The van Brederode family was at the center of the opposition. In 1470, David of Burgundy imprisoned Gijsbrecht van Brederode and his brother Reinoud II van Brederode, and had them tortured. This action stirred up the century old animosity between the Hooks who supported the family van Brederode and the Cods who supported Burgundy. A civil war broke out that lasted until 1474.The status-quo returned, until a Second Utrecht Civil War broke out in 1481.
Question: How many years after David of Burgundy had been appointed as bishop of Utrecht did he imprison Gijsbrecht van Brederode and his brother Reinoud II van Brederode?
Answer: 14