<Tr> <Td> Stephen Harper </Td> <Td> none </Td> <Td> none </Td> <Td> none </Td> </Tr> <Tr> <Td> Justin Trudeau </Td> <Td> none </Td> <Td> none </Td> <Td> none </Td> </Tr> <P> Only seven Prime Ministers have served in the military: </P> <Ul> <Li> Four Prime Ministers served in volunteer militia units (see Canadian Militia) attached to the British Army in Canada in later part of the 19th century </Li> <Li> One Prime Minister (Trudeau) was a cadet (not a full member) of the volunteer Canadian Army during World War II </Li> <Li> Only Diefenbaker and Pearson served as officers and overseas (during World War I) </Li> <Li> Seven Prime Ministers were members of the Army (none in the Navy or Air Force) </Li> <Li> One Prime Minister (Pearson) served in a non-Canadian military unit, the Royal Flying Corps (later RAF) during World War I </Li> </Ul>

How many canadian prime ministers served in the military