Two key things to keep in mind while looking for primary sources in databases.
TIPS
Language has changed over the centuries, and it is often difficult to speak like - and think like - our 17th century ancestors.
Words like college, race, "Indian," meant different things, and concepts like gender or nationalism didn't even exist.
As an example, a search for "gender" in Colonial America only yields 2 results, and only then relating to grammar rules.
Most primary source databases will have "thematic" filters to get you started. Before keyword searching, start there. See what curated documents come up. From those documents, see what terminology is being used by contemporaries.
Begin with basic searches and do not be too complicated. DO NOT USE TOO MANY TERMS AT ONCE
Be sure to use period-specific language.
Do NOT search a bunch of terms. This will give more, not less, false its.
Most Irish American newspapers don't cover this time period. Best bet is Pilot for 1863. Unfortunately the Irish-American stops coverages in May 1863 and the rest don't cover the 1860s. Not to worry, there are some really interesting articles in Pilot.
It might be interesting to compare the accounts in Pilot to other American newspapers.
Searches in our African-American historical newspaper databases don't work great, and only one African-American newspaper in the LoC list is active in 1863. There are articles in it, but they are in French.
Accessible Archives "African American Newspapers" works great. search "new york" limited to july 1 1863 to aug 1 1863. Another search for Irish for that time period also brings up interesting materials.
It may also be helpful to know more about the individual newspapers (political info, circulation, etc). See: