I've found the reference to "masked battery." At the time I first read it, I (rather unconsciously) defined "masked" as hidden, not realizing "masked battery" had a specific military definition that also included a specific type of location and way it went into action. Continued on in my reading, until the 3rd or 4th time I saw the term masked battery, then became more curious. Checked the original definition on this thread, and briefly searched elsewhere for a definition, without success. Then asked my question in post 2 of this thread.
The relevant sentence is the final one in the quote below:
"The Union army had been pressed back within half a mile of the Tennessee. A desperate and final struggle was now to be made. About four o'clock, after half an hours comparative quiet, the deepmouthed guns again opened; the roll of musketry was heard in continuous volleys, the wild tumult, the wierd shriek, the crashing timber, all bespoke the terrible conflict. The battleground has become fearfully contracted; the enemy's shell fall into the river and explode amid the transports! Another advance is ordered. The shattered brigades of Beauregard enter the ravine and close up on the contracted lines, protected by the siege guns. 'Three different times,' reports one of the commanders, 'did we go into that 'valley of death,' and as often were we forced back.' Another reports: 'A murderous fire was poured into us from masked batteries of grape and canister and also from rifle-pits.'"
De Hass, Colonel Wills. The Battle of Shiloh. 1878. Served at Shiloh in the 77th Ohio, Sherman's division. (Unfortunately, the web page reproduces it as one big long page with no subdivisions. The paragraph quoted is paragraph number 14 from the top.) Full text here:
http://www.civilwarhome.com/shilohbattle.htm
Thanks again for all your assistance as I try to understand what my gg grandfather might have seen and done. My lack of military knowledge really hinders me, hence my joining this board. Apologies for my (inadvertent) misstatements and misunderstandings, I mean no disrespect.