‘Flags of our Fathers’, while a good film, does not entirely depict the preparations made by the US for the Battle of Iwo Jima. The film depicts a scene where the fleet is firing on Mt. Surabachi, this scene is quickly over and the invasion begins the following day. It does indeed appear that in that scene they are just: ‘shooting at the mountain’, to give the dramatic impression of a pre-invasion bombardment. The reality is way more complex and involved. Considerable effort, planning and innovation had gone into target identification and direction of gunfire support and aerial bombardment in the lead up to the invasion. The US had learned a great deal from previous landings and so had the Japanese. This battle showed a change in defensive tactics by the Japanese and the perfecting of amphibious operations by the US. That being said there were still considerable lesson learned from this operation.

Japanese documents had been captured by the US during the invasion of Saipan (June 1944), which gave the planners for the Iwo Jima invasion a fairly good picture of the disposition of units and fortifications on the island. Carrier strikes and Army Air Corps bombing missions, in the lead up to the battle also included photographic intelligence missions, captured enemy maps and existing hydrographic maps were also useful. Japanese preparations on Iwo Jima intensified after the fall of Saipan and the US sought to update and review as much intelligence on the Japanese order of battle and fortifications on the island, prior to the invasion. Naval and Army Air Corps photo reconnaissance squadrons contributed hundreds of sorties to document the island, bomber strikes from the 7th Air Force also recorded strike photographs from their missions. Photo interpretation units of the Naval and Marine echelons worked together to create the Joint Situation Map in early December, 1944. This was followed by the Joint Enemy Installation Map in January of 1945, which lead to the final Enemy Installation Map issued to all organisations on the eve of the battle. Japanese fortifications and beach defences were substantiated by Submarine reconnaissance in December of 1944. In the lead-up to the battle it was noted that the aerial bombardment of the island, which had lasted 74 consecutive days, (not 20 days, as mentioned in the film) had negligible effect on defensive preparations on the island, which has continued to intensify. At the start of the bombardment campaign 450 Japanese fortifications were recorded by the US, afterwards 750 were recorded. The initial bombardment was set for three days of naval gunfire and aerial bombing. Planners wanted ten days, but various reasons such as ammunition logistics and a planned diversionary raid on Tokyo drew this down to three. Due to this short target preparation timeframe, extra photographic interpreters were attached to the planning staff to assist in the recognition and damage assessment on targets.
Each priority target was given a serial number, which was recorded in a Kardex filing system. Kardex is a kind of ‘visible filing system’ which can be updated easily. Targets were given Priority A, B or C status, Priority A indicated a threat to aircraft, ships and UDT operations and Priority B indicated a threat to ship-to-shore movement and landing operations, Priority C targets were caves, ammunition dumps and bivouac areas. Targets were also prioritised into groups that were most effectively serviced by naval gunfire, those that were more suited to aerial bombardment and a third grouping of a combination of both. The Marine advance off the beaches was, in part, halted by enemy emplacements that had remained hidden until they began firing on the UDT (Underwater Demolition Teams) and minesweeping operations of D-2. (D-2 means ‘D-Day minus two) This shows that Priority A targets were still being discovered the day before the landings, despite the intelligence gathering efforts. Each fire mission, naval or aerial, conducted against these targets was logged in the Kardex system against the corresponding serial. The serial was updated to reflect the fire mission and then cross-referenced to the photographic records coming in, to assess the damage and if needed, reallocate the serial. This system was workable, but bad weather hampering aerial reconnaissance and gunfire spotting, as well as large numbers of serials and short time frame, reduced the quality of the system in some cases. During the preparations to the immediate battle, from early December 1944 to D-1, the photographic unit processed over 57,000 photographic prints of all sizes. 18,450 maps were produced in preparation for the battle. The map of the ‘Naval Gunfire Areas of Responsibility’ shown in the briefing scene in the film, is the D-1 map. D-2 and D-3 had a different map. The D-1 map allocates the USS New York to fire on the beach, whereas it was firing inland on the previous map. Ships tasked to attack close-in to targets, were issued with low angle oblique photographs to assist in target recognition. A remarkable part of the preparations for this battle were the Underwater Demolition Teams which went in on D-1, in daylight and under fire, to inspect and clear the beaches of obstacles and mines. On the morning of the amphibious assault on the 19th of February, naval gunfire had switched from ‘painstaking fire for destruction’ to ‘area neutralisation and beach preparation’. The H-Hour (H-Hour means the hour the invasion force arrives on the beach) invasion phase had been immediately preceded by area fire from the big 16 inch guns as well as rocket, mortar fire and air strikes. A rolling barrage from 5 inch guns was established ahead of the advancing Marines and was lifted to meet the estimated advances. However, when the advance was halted, the barrage was repeated on the prearranged target areas. This is not shown in the film.

Criticism of the from planners cite that the number of high priority targets were too numerous to be effectively reduced in the three days of naval bombardment. Air operations were hampered by bad weather and AA fire, including a large B-24 raid on Surabachi scheduled for D-3 which was turned back due to low cloud. Air bombardment did record multiple targets destroyed, especially as aircrew grew more familiar with target location. Naval Bombardment was also considered very effective in after action reports. The various US intelligence echelons across the services, worked together to create a complex and inventive system to manage the large number of targets on the island in the time allotted. Japanese preparations were of a highly durable and in some cases not detected by the considerable efforts made by the US, which led to considerable losses despite the pre-invasion preparations. While I would have liked to have seen a film showing the aerial spotting planes, Kardex fling systems, shipboard printing presses and target allocation meetings, I think that Eastwood probably made the right decision to just show the awesome old battle ships like the Nevada just shelling the hell out of Surabachi.

Sources: Iwo Jima: Amphibious Epic, by Lt. Col. Whitman S. Bartley USMC. 1954. Action Report: Iwo Jima, February 1945. Commander Task Force 52 and Commander Amphibious Group One. I can recommend this short film on the subject as well.