Why did King Charles I need to call Parliament in 1640 after years without it?

King Charles I was forced to summon Parliament in April 1640—ending his 11-year period of "Personal Rule"—primarily because he desperately needed to raise funds for a military campaign against the Scots.12

The conflict arose from Charles’s attempt, supported by his close adviser William Laud, the archbishop of Canterbury, to impose Anglican religious practices and a modified Book of Common Prayer on the Scottish Church. This sparked widespread resistance, leading to the Bishops’ Wars. After the first campaign ended in a truce, Charles discovered the Scots were intriguing with France and decided to use force again.324

Having exhausted traditional revenue sources—such as the controversial ship money tax—during his years of ruling by decree, the King lacked the financial resources to sustain a second military expedition. However, the resulting Short Parliament refused to grant subsidies until their grievances were addressed, leading Charles to dissolve it after only a few weeks. He was ultimately forced to call the Long Parliament later that year following further military failures against the Scots.1342