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Pneumonia, an infection of the lungs, ultimately claimed Merle Haggard's life. This medical condition, characterized by inflammation and the accumulation of fluid in the air sacs of the lungs, severely impacted his respiratory system. With symptoms such as fever, chills, and difficulty breathing, pneumonia poses a significant threat, especially to those with compromised immune systems. Sadly, despite medical intervention, Haggard succumbed to the complications of double pneumonia.