May have served in the War of 1812, unfortunately the name John Shipley seems to be have been pretty common and the 1812 war records do not provide anything more than the name.
Not sure this 1850 Census source is at all correct. John died in 1840 and the names don't seem to be his children.
Sources
Census Records:
"United States Census, 1850," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MD4D-F2G : 4 April 2020), John Shipley, Carroll county, part of, Carroll, Maryland, United States; citing family 578, NARA microfilm publication M432 (Washington, D.C.: National Archives and Records Administration, n.d.).
Find a Grave, database and images (accessed 14 May 2020), memorial page for John Shipley (26 Apr 1768–9 Nov 1840), Find A Grave: Memorial #28734923, citing Ebenezer United Methodist Church Cemetery, Winfield, Carroll County, Maryland, USA ; Maintained by Jennifer Shipley (contributor 47002081) .
Information from the import of My Family File.ged on Aug 31, 2011 by Jane Entwisle.
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DNA Connections
It may be possible to confirm family relationships with John by comparing test results with other carriers of his Y-chromosome or his mother's mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree: