Why is my Camera not rotating properly?

Hey guys, I have this script for an RTS style camera. It works fine with the only exception being, it doesn't rotate my camera properly. I have Q and E keys set up for rotation which work fine however, it doesn't change the cameras "forward" angle. (ex. facing North -> turn camera East -> move facing East -> Camera moves North)

Can anyone help me with this?

 public class RTSCamera : MonoBehaviour {
     //how fast the camera scrolls.
     public float HorizontalSpeed = 40;
     //how fast the camera adjusts to it's new height.
     public float VerticalSpeed = 40;
     //how fast the camera turns.
     public float CamRotSpeed = 40;
     //how high the camera is.
     public float CamDistance = 80;
     //current distance of the camera.
     public float CurrentDistance;
     // Update is called once per frame
     void Update () {
         /*these are the WASDQE inputs*/
         float H = Input.GetAxis ("Horizontal") * HorizontalSpeed * Time.deltaTime;
         float V = Input.GetAxis ("Vertical") * VerticalSpeed * Time.deltaTime;
         float R = Input.GetAxis ("Rotation");
         //this tells the camera to move as long as the respective button is pressed
         transform.Translate(Vector3.forward * V, Space.World);
         transform.Translate(Vector3.right * H, Space.World);
 
         //making the camera rotate on global Y axis.
         if (R != 0) {
             transform.Rotate (Vector3.up, R * CamRotSpeed * Time.deltaTime, Space.World);
         }
 
         RaycastHit ground;
         if (Physics.Raycast (transform.position, new Vector2(0,-1), out ground, 500)) {
             CurrentDistance = Vector3.Distance (transform.position, ground.point);
             Debug.Log (ground.collider.name);
             Debug.DrawLine(transform.position, ground.point, Color.cyan);
         }
 
         if (CurrentDistance != CamDistance) {
             float camDiff = CamDistance - CurrentDistance;
 
             transform.position = Vector3.Lerp (transform.position, transform.position + new Vector3 (0, camDiff, 0), Time.deltaTime);
         }
         }
 }