Tyler commanded the reserve during the battles of Chancellorsville and Gettysburg, where many of his guns were used to help repel Confederate attacks on such Union positions as Cemetery Ridge and Cemetery Hill, as well as during Pickett's Charge on July 3.
Tyler kommanderede reserven under slagene ved Chancellorsville og Gettysburg, hvor mange af hans kanoner var med til at slå sydstatshærens angreb på unionsstillinger såsom Cemetery Ridge og Cemetery Hill tilbage, foruden Picketts angreb den 3. juli.