As I remember this trilogy it starts shortly before  the French and Indian War and follows the generations of the family through the war of 1812.  I think the main character in the first book is named Adam.  The family owns a farm.  A key scene I remember is when someone is dying of a fever and their family member takes pity on them and gives them water to comfort them even though it is strictly against the doctor’s orders– the medical practice being so wrong really made an impression on me.  I took these three books out of the Park Ridge, IL public library when I was in junior high and read them several times.   I think they were written in the early sixties but it could be earlier.  There are a lot of descriptions of colonial life and the generational tensions about fighting in wars.  They were longer and more advanced reading than Johnny Tremain.