What initial action should be taken upon identifying a casualty with severe bleeding?

Applying direct pressure to the wound is the most critical initial action when addressing a casualty with severe bleeding. This technique is fundamental because it helps to control hemorrhage by promoting clot formation at the site of injury and reducing the loss of blood. Immediate attention to the wound can significantly stabilize the casualty and potentially save their life. Direct pressure is often the first step in managing trauma before considering other interventions.

In contrast, starting an IV line to provide fluids is an important action but should follow after immediate bleeding control measures have been initiated. Administering pain medication may help with the casualty’s comfort but does not address the urgent need to stop the bleeding. Assessing the casualty's level of consciousness is vital in a broader assessment but should not take precedence over controlling severe hemorrhage, which is a life-threatening condition. Prioritizing direct pressure allows for a more effective response to the immediate needs of the casualty.