 Operation Masher began officially on the morning of 28 January 1966, low clouds, wind and heavy rain prevented the movement of artillery to Firebase Brass.Lacking supporting fire, Moore cancelled the 2/12th Cavalry's mission.In the meantime, PAVN/VC fire downed a CH-47 helicopter at Landing Zone Papa north of Bong Son and Kampe responded by sending a 1/7th Cavalry company to secure
the crash site.