## Facts

- In 1914, Portugal was neutral in World War I and administered Angola, bordering German South-West Africa.
- Portugal’s colonial authorities restricted exports of food to the neighboring German colony, prompting a German effort to negotiate supplies and communications.
- On 19 October 1914, a German delegation approached the Portuguese fort at Naulilaa near the border; severe language barriers and mutual suspicion led to a confrontation in which Portuguese soldiers killed three German members of the delegation.
- In December 1914 through early 1915, German forces conducted punitive raids into Angola, including an attack on the Naulilaa post and other locations along the border, causing casualties, destruction, and significant disruption that contributed to a major Portuguese retreat.
- Germany did not first seek reparation or satisfaction through diplomatic channels or other peaceful means for the October 1914 deaths before launching the raids.
- Portugal sought reparation for extensive losses in Angola, including destruction of posts, requisitions, looting, and consequential losses tied to the retreat and broader disruption.
- An ad hoc arbitral tribunal constituted under the Treaty of Versailles heard the dispute and issued a first award determining liability in principle.

## Issues

1. Whether Germany incurred international responsibility for damage caused by its military operations in Portuguese Angola before Portugal entered the war.
2. Whether Germany’s incursions were legally justified as reprisals (or self-defense) in response to the Naulilaa incident, given Portugal’s neutral status.
3. What conditions general international law imposed on lawful reprisals, including prior wrongful act, prior demand for redress, necessity, and proportionality.
4. Whether Germany was liable only for direct damage or also for indirect losses that followed from the incursions.

## Decision

- The tribunal held Germany internationally responsible in principle for damage caused by its operations in Portuguese Angola during Portugal’s neutrality.
- The tribunal found the German raids constituted unlawful reprisals because:
  - the Naulilaa incident was not established as a clear prior international wrong attributable to Portugal warranting forcible retaliation,
  - Germany failed to demand satisfaction or seek peaceful redress before using force, and
  - the raids were disproportionate to the precipitating incident and violated the rights of a neutral state.
- The tribunal concluded Germany’s responsibility could extend beyond immediate physical destruction to certain indirect losses sufficiently connected to the unlawful operations, subject to a causation requirement later developed in the quantum phase.

## Legal Principles

- Reprisals under general international law presuppose a prior internationally wrongful act attributable to the target state; absent a clear prior wrong, punitive action is unlawful.
- A state must, as a condition for lawful reprisals, first seek reparation or satisfaction by peaceful means before resorting to coercive measures.
- Reprisals must satisfy necessity and proportionality; measures “out of all proportion” to the motivating act are excessive and unlawful.
- The rights of a neutral state, including territorial inviolability, limit the permissibility of reprisals; neutrality cannot be overridden absent strict satisfaction of the conditions for lawful reprisals.
- State responsibility may include compensation for indirect damage when it is the immediate, normal, and necessary consequence of the internationally wrongful act.

## Conclusion

The tribunal held Germany liable in principle for losses caused by its punitive raids into neutral Portuguese Angola, reasoning that the raids were unlawful reprisals because Germany neither established a clear prior wrong by Portugal nor sought peaceful satisfaction, and because the measures were disproportionate and infringed neutrality; Germany’s responsibility could also reach proximate indirect losses caused by the incursions.


Portugal v. Ger. (Naulilaa Arb.), 2 R.I.A.A. 1011 (1928)