Organizing units like we do cities would be nearly impossible; units are typically assigned to an Order of Battle; their place in the military hierarchy. These OOB are usually well documented and as a government document can usualy be found in archives. In this regard it would be easy to break down the units into categories.
The problem is that an OOB is much more fluid than national and administrative boundaries, with units transferred, re-roled and renamed, zero-strengthed, deactivated and reactivated, reconstituted, and amalgamated as the needs and size of the military they are part of change. In periods of mobilization existing units may provide 'formed bodies' or sub-units which then become part of other units, even though they usually maintain their regimental 'lineage' to the unit from which they were formed, and rejoin those units when they are disbanded. The lineage of a military unit is much more like a family tree than a category.
To illustrate how complicated it might be to categorize units I will give a brief (but inconcise) history of the 48th Highlanders of Canada:
The Regiment was formed in Toronto in 1891. At the time they were assigned to Military Distict No. 2, Canadian Militia (non-permanent).
In World War 1 the 48th Highlanders raised 3 battalions for overseas service: the 15th Battalion (48th Highlanders), Canadian Expeditionary Force (CEF) which was assigned to the 3rd Infantry Brigade, 1st Canadian Division; the 92nd Battalion (48th Highlanders), CEF and 134th Battalion (48th Highlanders), CEF which were essentially taken apart for reinforcements when they arrived at the front. Once a 2nd Canadian Division had been raised, the 1st division became part of a higher organization, the Canadian Corps. The 92nd and 134th Battalions were eventually disbanded and their remaining personnel that had not been used as replacements were absorbed into other Battalions. At the end of the war the 15th Battalion was disbanded and its surviving personnell were largely absorbed back into the 48th Highlanders.
The 48th Highlanders as a complete organization were never mobilized in World War 1, and remained part of Military District No. 2, conducting recruiting and training throughout the war. The current Regimental Colours of the 48th carry battle honours for Ypres, Somme, Vimy, Passchendaele, Amiens, and numerous other famous battles of World War I, because they perpetuate the traditions of the (disbanded) Battalions they raised.
Just at the start of World War 2 (Sept 1939) the Canadian Militia was reorganized and renamed the Canadian Army (Reserve) and the 48th Highlanders thus became part of the 6th (Toronto) Brigade, Military District No.2, Canadian Army (Reserve)
For World War 2, the 48th Highlanders mobilized the 48th Highlander of Canada, Canadian Active Service Force, which was redesignated 1st Battalion, 48th Highlanders of Canada, 1st Canadian Infantry Brigade, 1st Canadian Division, 7th (British) Corps, 2nd British Expeditionary Force. By 1941 the 7th Corps was disbanded primarily as a result of the formation of Canadian Corps. The 1st Canadian Division was then detached to the famous British 8th Army participating in the invasion of Sicily known as Operation Husky. During this time 1st Canadian Infantry division was placed under command of the British XXX Corps. although it was still part of the Canadian Corps. Eventually, 1 Canadian Division was reunited with the rest of what had become I Canadian Corps (after II Canadian Corps became operational), and with the deployment of First Canadian Army Headquarters in 1944, the 48th completed the remainder of World War 2 as 1st Battalion 48th Highlanders of Canada, 1st Canadian Infantry Brigade, 1st Canadian Division, I Canadian Corps, First Canadian Army.
Meanwhile back in Canada the 48th Highlanders that remained in 6th Brigade, No. 2. Militia District, continued recruting and training and mobilized the 3rd Canadian Infantry Battalion (48th Highlanders of Canada), Canadian Active Service Force in June of 1945. This unit was destined for the Pacific theatre, but obviously did not see action as the end of hostilities came in August/September of that year.
The wartime battalions were disbanded or absorbed back into the 'parent' unit when they returned to Canada.
The 48th Highlanders remained part of the Military District No. 2., which became the Toronto Militia District, Central Militia Area, Canadian Army (Militia). After another reorganization the 48th Highlanders became part of 32nd Canadian Brigade Group, Land Force Central Area (LFCA), Canadian Army, Canadian Forces. This past year LFCA was renamed 4th Canadian Division.
The 48th Highlanders have a relatively short and uncomplicated history compared to many units that exist or have existed. As you can hopefully see, creating all the relevant hierarchial categories accurately in the same manner as cities and towns, would be quite a complicated and exhaustive undertaking.
As I see it, the only way to further categorize units, although it is somwhat imprecise, is by military role such as: [[category:Canadian Military Units, Infantry, 48th Highlanders of Canada]]. In some cases this should be further categorized by years if a unit is disbanded or re-roled and the name or designation 'recycled', for example [[category: Canadian Military Units, Headquarters, 4th Canadian Division]] should have separate entries for 1916-1919, 1940-1946, and present.
Notes and links could be added to the category pages to show a unit's lineage. For example "Infantry, 42nd Brockville Battalion" evolves over the years as 1. "infantry, 42nd Lanark and Renfrew Battalion of Infantry"; 2. "infantry, 42nd Lanark and Renfrew Regiment"; 3. "infantry, The Lanark and Renfrew Regiment"; 4. "infantry, The Lanark and Renfrew Scottish Regiment, 1927-1946"; 5. "anti-aircraft, 59th Light Anti-Aircraft Regiment (Lanark and Renfrew Scottish)" 6. "infantry, The Lanark and Renfrew Scottish Regiment, 1959-1992"; 7. "anti-aircraft; 1st Air Defence Regiment (Lanark and Renfrew Scottish)"; 8."artillery, 42nd Field Regiment (Lanark and Renfrew Scottish)"
