Lieutenant Colonel O'Neill's concept of operations was for B Company to ambush likely enemy routes in the vicinity of a fire trail from YS455544 to YS 463553 while C Company and D Company with APC and tank support, conducted reconnaissance in force to the north west and south east of the established ambush positions, with the aim of either destroying the enemy or forcing enemy groups to move into the ambush killing grounds. Due to the threat of anti-personnel M16 mines, whenever practicable, infantry moved in closed down APCs with tanks in front of the APCs to clear the way. This tactic was successful and there were no casualties from M16 mines when troops moved in this manner. Likely enemy withdrawal routes which could not be ambushed were fired upon by mortars, artillery and aircraft.

Implementation of the concept soon produced results. On 18th February C Company discovered a major enemy troop concentration of D445 Battalion located in a valley of an area called Minh Dam Secret Zone by the Vietcong.

Valley of the Minh Dam Secret Zone

Initial contact was with three enemy only, one of whom was captured. The prisoner, a sixteen year old youth, identified himself as a member of Cl-D445 Battalion and accompanied Lieutenant Colonel O'Neill in the command and control helicopter from which he identified enemy positions at which, he claimed, thirty to forty of his comrades were located. It was later established that the whole of D445 Battalion was in the area. C Company with support from 2 Troop A Squadron 1 Armoured Regiment and 3 Troop B Squadron 3 Cavalry Regiment moved forward to assault the suspected bunker position. Contact was made with the enemy when the leading APC was hit by an RPG round and caught fire.

A heavy firefight followed initial attempts to recover the APC failed; however, five of the seven occupants were rescued under fire, from the vehicle. For their part in this action Corporal Coe of C Company, and Corporal Macey of B Squadron 3 Cavalry Regiment were each awarded the Military Medal. Following the rescue of the APC occupants C Company withdrew and regrouped to attack again.

Meanwhile Lieutenant Colonel O'Neill had ordered the redeployment of B Company and D Company to ambush positions from which they could block enemy egress out of the valley to the north and east. Artillery and air strikes were directed onto the steep cliffs to the southwest and along both sides of the valley. It appeared that the elusive D445 Battalion would be forced to fight or to accept heavy casualties during any attempt to escape. There is no doubt that the enemy appreciated the significance of B and D Companies' moves, as during their deployment B Company was involved in four contacts, which resulted in four members of the supporting APC Troop and five B Company soldiers being wounded. Four APCs were slightly damaged by RPG fire; however, B Company was not prevented from completing its mission. Six enemy bodies were later found in the areas of the contacts.

The above contacts did delay B Company's movement. As a result D Company reached its ambush location first and B Company was forced to pass through the D Company positions. During one of the B Company contacts friendly APC machine gun fire hit 11 Platoon, wounding ten soldiers, two of whom remained on duty.

Meanwhile the C Company Group had again assaulted into the valley, inflicted heavy casualties on the enemy and recovered the burnt out APC. Six C Company soldiers were wounded during this assault.

By last light on 18th February the Battalion was favorably deployed for a coordinated first light attack. However this concept was changed when it was directed that the enemy positions be the target of a B52 strike. The battalion withdrew to enable the strike to occur. D445 Battalion took advantage of this withdrawal and escaped to the east along the routes which had been blocked by B Company prior to their withdrawal.

On 21st February, following the B52 strike and intensive artillery fire, three rifle companies, with tanks and cavalry still in support, redeployed to the Long Hai Hills. Two Vietnamese Regional Force (RF)companies began operations in the area. Lieutenant Colonel O'Neill's concept of operations was that the two RF Companies, C Company and D Company would carry out bomb damage assessment and reconnaissance in force, while B Company ambushed likely enemy routes. A Company later joined the remainder of the Battalion, following operations in the east of Phuoc Tuy Province, and began reconnaissance and ambush tasks.

During the following ten days numerous caches were discovered and more than 200 enemy bunkers destroyed. 4 Platoon B Company achieved notable results when ten of an enemy party of eleven were killed by our fire, or by their own mines while attempting to escape. Many enemy dead, killed during earlier fighting, were found unburied. Casualties suffered by the Battalion during this period were very light, except on 28th February when a platoon was involved in two mine incidents. Prior to these incidents the platoon had been moving at a rate of 100 metres per hour clearing a route to an ambush position.

At 1100 hours an M26 grenade booby trap with an anti-lifting device, was located. An engineer party moving to neutralize the booby trap initiated an M16 mine causing seven soldiers to be killed and thirteen to be wounded. While guiding a Dustoff helicopter into an area cleared of mines a member of the platoon stepped out of the cleared area detonating a further M16 mine which killed one and wounded three soldiers. One of the wounded later died.

During Operation Hammersley the enemy suffered 42 killed in action. This number was confirmed by body count; however unconfirmed reports have indicated that the number of enemy dead may have exceeded one hundred. Other significant enemy losses were:

1 prisoner.

70 personal weapons.

5 crew served weapons.

Approximately 1 1,000 small arms rounds.

250 grenades, mortar bombs and mines.

2000 lbs of food.

Large quantities of medical supplies and equipment.

Friendly losses were 1 1 killed and 59 wounded.

The Battalion's operations had proved that it was possible to force large enemy groups out of their mountain hides. This had the secondary, but probably more important result, of encouraging Vietnamese Regional Force Companies to operate in the area. From the enemy’s view point two significant results followed Operation Hammersley. Firstly he was shown that his previously safe haven was vulnerable. Secondly the local population was given substantial proof that guerilla control of populated areas near the Long Hai Hills was not inviolate.

The Battalion obtained valuable experience in mobile operations involving the use of APCs and tanks, and, once again, the value of close liaison with neighbouring headquarters was demonstrated.

Below is an extract of a letter of commendation, received from Lieutenant General Julian J. Ewell, Commanding General 1 1 Field Force Vietnam:

"Dear Brigadier Weir,

I am enclosing a letter from Lieutenant General Do Cao Tri, Commanding General, 111 Corps and 111 CTZ, commending the 8th Battalion Group for its combat achievements on 21st February 1970 in the Minh Dam Secret Zone. It gives me great pleasure to add my commendation to that of General Tri. The dedication and true professionalism demonstrated by your forces have significantly enhanced our common efforts against a very stubborn enemy.

Only by grinding away at the enemy, capturing his supplies and denying him his sanctuaries as you are doing, will we be able to force the enemy out of Phuoc Tuy Province and eventually out of the Republic of Vietnam.

I wish you continued success in the future and request that you pass on to your soldiers our appreciation for their outstanding performance.

It will be seen that our continuing combined operations in the Long Hais are significant and important. "