This is a great book, although I don’t say it is an easy read. It seems unbelievable that Sack is not included amongst the 52 “Key Thinkers on Space and Place” listed by Hubbard, Kitchin & Valentine (2004) or the book included in their 26 “Key Texts in Human Geography”(2008).That he and it aren’t included highlights the wrong turn taken by modern geography.
Geography describes the complexity of spatial relations including how they varied over time. Territories are socially constructed spatial arrangements leading to the questions, “who is controlling a territory and for what purpose?”

Territoriality is the key connection between society and space, but one which geography continues to keep in the background even after Sack’s “Human Territoriality”. It shouldn’t.
Primitive societies use it only to a limited extent, for instance in fencing off gardens from wild or grazing animals. A band or people are defined culturally or by language in relation to events. Amongst Australian Aborigines totemic groups are associated with places from which the totemic ancestor apparently emerged and to where it is believed that on someone’s death his spirit returns. Mythical bestowal of the land on a people including ancestors leads to community “ownership” of place.
A feudal lord may know a village belongs to him, but he and the villagers may not have known exactly where the village land began and ended.
Territoriality is classification by area rather than category or group. It is signaled. (See for instance my posts on Jersey Parish Iconography). It involves restricting provision of services to a territory, excluding others eg would be immigrants and restricting those leaving eg the escape of prisoners. Functions are moulded into territory.
Sack describes “tendencies” which follow the strategy of territoriality. They are of increasing complexity in the modern capitalist world and it is only here that all the tendencies operate. In practice territoriality isn’t a single strategy, but is made up of a series of intertwining territorial strategies.
Territoriality exists at different scales, in the way a church is divided between areas of differential sanctity and at a bigger scale the way the church is organised between patriarchies, bishoprics and parishes.
The exposition is not always easy to follow. Instead I recommend reading the case studies, which follow exposition of the theory, and which provide examples of the tendencies arising from territoriality, and only then rereading the theory.
Some of the tendencies:
Territoriality provides an efficient means for differential access to resources concentrated in time or space. It can increase efficiency to a point where there are spillovers or mismatches. Thus, “the static nature of boundaries [means] they need to be continually readjusted to minimize mismatches between responsibility and effects.” In Jersey, unusually, parish boundaries essentially have not been adjusted since the 11th Century.
Territoriality displaces attention from relationships between the controller and the controlled into statements like, “it is the law of the land” or “you can’t do that here”.
Territory can be emptied and filled. Modern architecture and planning allows warehouses and factories to be re-partitioned, re-fitted and used for new purposes, retail, residential,restaurant or whatever.
Territoriality is space filling. This contributed to medieval kingship where a king could at the same time be ruler of more than one jurisdiction. Sack describes the American territorial system where the Constitution provided for new States which had yet to be created or imagined, a conception of territory in the abstract. Abstraction was provided by geometric boundaries and a view of the land as empty and fillable ignoring “occupation” by native Indians. This is contrasted with the Ulster Plantations which conformed to existing Irish settlements and landholdings. The Constitution also allowed secession leading to the American Civil War.
Agricultural communities are territorial with a tendency to subdivide land as population increased. Territoriality was used as a strategy when society moved from reciprocity to class-structured re-distribution.
Territoriality helps explain the variety of land holdings between communally organised common land, open fields, strips and block holdings, including demesne and glebe land. For a good recent study of such landholdings see “Not so common fields; the making of the East Anglian landscape” by Edward Martin (2008).
Modernisation in parallel with agricultural and industrial “revolutions” and demographic take off resulted in uprooted peasants, armies of vagabonds and burgeoning town populations. The response from authority was to adopt the territorial strategy of isolating such “deviants” in prisons, poor houses and asylums, separating those who couldn’t or wouldn’t work from those who could and putting the “work-shy” to work in workhouses. Some of the same applied in placing children in schools and soldiers in barracks.
Territories may be organised hierarchically. With increased hierarchy there is a tendency to impersonal relationships between governor and governed. That Jersey’s parishes are essentially not part of a hierarchical structure helps explain their unusual quality as territories which are places.
City streets in the past were full of bustle and innumerable activities. Such occupation has been “thinned” and dedicated to vehicle movement, dividing up urban space. We are seeing the current debate about “reoccupation” of the streets by pedestrians, cyclists, cafés and entertainers, a debate which has increased with Covid-19 “LockDown” and its subsequent relaxation. Changing administrative boundaries and territorial hierarchy may mean it is unclear to users which authority has reserved road use for vehicles.
Thought provoking. I have started applying Sack’s theory of territoriality to work on island territories generally and Jersey in particular.