In what year(s) does the retention of Gibraltar take on new significance?

The retention of Gibraltar takes on new significance in 1869 and 1875 primarily due to the strategic impact of the Suez Canal's opening and the growing maritime power of Britain during this period. The Suez Canal, which opened in 1869, created a critical voyage route from Europe to Asia, making Gibraltar an even more vital naval and coaling station for British ships traveling to and from the Indian and Pacific Oceans. This further solidified its role as a key strategic stronghold in global naval dominance.

During these years, Britain emphasized its empire's connectivity and trade routes, necessitating the secure retention of Gibraltar as a critical gateway into the Mediterranean Sea. The geographical location of Gibraltar allowed Britain to monitor maritime traffic and protect its interests in the region, reinforcing its importance beyond just a mere territorial claim.

The other time periods mentioned do not exhibit the same level of strategic relevance concerning maritime and imperial interests, particularly regarding the enhanced global trade routes established in the late 19th century.