How massive was the June 6, 1944, D-Day invasion?

How massive was the June 6, 1944, D-Day invasion? 

How massive was the June 6, 1944, D-Day invasion? Well, this photo gives part of the

 answer. It shows anding ships putting cargo ashore on Omaha Beach, at low tide during 

the first days of the operation, mid-June, 1944. Note barrage balloons overhead and Army 

"half-track" convoy forming up on the beach. A barrage balloon is a large balloon tethered with metal cables, used to defend against low-level aircraft attack by damaging that 

aircraft on collision with the cables, or at least making the attacker's approach more 

difficult. Some versions carried small explosive charges that would be pulled up against 

the aircraft to ensure its destruction. Barrage balloons were only employed against low-

flying aircraft; the weight of the longer cable made them impractical for higher altitudes.