[1] On 28 June 1969 during Operation Montgomery Rendezvous the ARVN 4th Battalion, 1st Regiment, 1st Division (1/1st) observed a large People's Army of Vietnam (PAVN) force moving south in the open near the base and called in airstrikes which killed 37 PAVN.

[3]: E-22 On 9 August during Operation Chicago Peak elements of the 1/1st at O'Reilly received two 75mm recoilless rifle rounds killing one and wounding 14.

On 12 August, an element of the 1/1st, in a night defensive position near the base, was attacked by an estimated PAVN company.

[3]: E-24 On 16 August 2 km southwest of O'Reilly the 3/3/1st with organic weapons killed 26 PAVN at cost of 10 dead and 12 wounded in two separate engagements.

On 22 August elements of the 1st Regiment found 20 PAVN bodies which had been killed by airstrikes the previous day.

At 05:10 on 23 August the 2/1/1st while in a night defensive position 5 km southwest of O'Reilly received a ground attack.

On 31 August the 3/1st, while on a ground reconnaissance near the base, found 20 PAVN bodies killed by air 6 to 12-hours earlier.

In the vicinity of the base on 20 September, ARVN elements contacted the PAVN units in two separate actions.

On the early morning of 24 September the 4/1/1st ambushed a PAVN force and killed 26 in the general vicinity of the base.

[3]: E-24–5 In mid-September, due to anticipated bad weather which would affect air operations, the ARVN Joint General Staff considered the evacuation of O'Reilly.

Firebase Barnett (10 km northwest of O'Reilly) was closed 18 September as part of the preplanned monsoon season relocation of units.

It was speculated that the PAVN attacks around O'Reilly were to divert allied attention from the logistical activity along the border and in Laos.