Soldiers

I've found many variants of the formal portraits shown below, mostly from World War I. It's impossible to know if their subjects came back, but the fading of this one suggests that it sat in a frame for many years and gradually faded:
Did he come back?

Some were taken in case the unthinkable happened:
Just in case...

Somehow very Canadian, very not-American. What is it?
WWI soldier

Because of all the to-and-fro of migration, quite a few people of Nova Scotian stock served in the American armed forces. Here's a brace of brothers (on the back: John's oldest boy... John's second boy I think it's the one in the Navy Arthur C. Roscoe son of John and Bertha):
brothers in the services

Another Doughboy:
another Doughboy

For another view of WW I activities, see extracts from a 3-foot panoramic view of the Jordan Marsh Rifle Club's Preparadness Parade, May 27 1916

World War II sparked an avalanche of picture-taking. Some images feature gravity-defying headgear:
How does the cap stay on?

Perhaps the hair is the single (triple?) most interesting element. This one is labeled "Elwood, Elwood Jr., and Anne as Elwood was leaving for Guam, May 14 1945":
Elwood, Elwood Jr., and Anne

IWW II also produced a lot of group photographs of military people in lines. These three are details from a Royal Canadian Army Medical Corps group at Petawawa Military Hospital, May 21st 1942:

RCAMC Petawawa detail
RCAMC Petawawa detail
RCAMC Petawawa detail

This one may help to explain why sailors are called 'gobs':
Radioman
For fuller explanation, consult the third sense at answers.com:

Probably shortening of earlier gobshite, wad of expectorated chewing tobacco, sailor. See gobshite.

 

...and while we're on the subject, consider all those folksongs about young maidens who dress themselves in sailor's clothing and go to sea, only to be rumbled by Wicked Captains...
Off to sea

From an earlier era, another case of two sons in the Forces (compare the ears...):
Two sons in the Forces

The Queen's Own Bellhops:
Queen's Own Bellhops

The Queen's Own Soupstrainers:
Queen's Own Soupstrainers

...and the Sackbut Corps:
trombone

This one memorializes a trip to French Cross, also called Morden, not far from the Greenwood airbase:
French Cross