"Thin Red Line" meaning in English

{
  "etymology_text": "William H. Russell, Times Correspondent at the Battle of Balaclava wrote that he could see nothing between the charging Russians and the British regiment's base of operations at Balaclava but the “thin red streak tipped with a line of steel”. The condensed phrase “the thin red line” came to represent British composure in battle.",
  "forms": [
    {
      "form": "the Thin Red Line",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "noun",
        "head": "the Thin Red Line"
      },
      "expansion": "the Thin Red Line",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "_dis": "62 38",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "72 28",
          "kind": "topical",
          "langcode": "en",
          "name": "Collectives",
          "orig": "en:Collectives",
          "parents": [
            "Miscellaneous",
            "All topics",
            "Fundamental"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "73 27",
          "kind": "topical",
          "langcode": "en",
          "name": "Military units",
          "orig": "en:Military units",
          "parents": [
            "Military",
            "Occupations",
            "Society",
            "People",
            "Work",
            "All topics",
            "Human",
            "Human activity",
            "Fundamental",
            "Human behaviour"
          ],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "The members the 93rd Regiment of the British Army who met the charge of the Russian cavalry at the Battle of Balaclava in 1854."
      ],
      "id": "en-Thin_Red_Line-en-noun-~fkggxPb",
      "raw_glosses": [
        "(historical) The members the 93rd Regiment of the British Army who met the charge of the Russian cavalry at the Battle of Balaclava in 1854."
      ],
      "related": [
        {
          "_dis1": "74 26",
          "word": "green line"
        },
        {
          "_dis1": "74 26",
          "word": "red line"
        },
        {
          "_dis1": "74 26",
          "word": "single yellow line"
        },
        {
          "_dis1": "74 26",
          "word": "thin blue line"
        }
      ],
      "tags": [
        "historical"
      ]
    },
    {
      "glosses": [
        "Any thinly spread military unit holding firm against attack."
      ],
      "id": "en-Thin_Red_Line-en-noun-gaodVy0u",
      "raw_glosses": [
        "(by extension) Any thinly spread military unit holding firm against attack."
      ],
      "tags": [
        "broadly"
      ]
    }
  ],
  "wikipedia": [
    "The Thin Red Line (Battle of Balaclava)"
  ],
  "word": "Thin Red Line"
}

{
  "categories": [
    "English entries with incorrect language header",
    "English lemmas",
    "English multiword terms",
    "English nouns",
    "en:Collectives",
    "en:Military units"
  ],
  "etymology_text": "William H. Russell, Times Correspondent at the Battle of Balaclava wrote that he could see nothing between the charging Russians and the British regiment's base of operations at Balaclava but the “thin red streak tipped with a line of steel”. The condensed phrase “the thin red line” came to represent British composure in battle.",
  "forms": [
    {
      "form": "the Thin Red Line",
      "tags": [
        "canonical"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {
        "1": "en",
        "2": "noun",
        "head": "the Thin Red Line"
      },
      "expansion": "the Thin Red Line",
      "name": "head"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "green line"
    },
    {
      "word": "red line"
    },
    {
      "word": "single yellow line"
    },
    {
      "word": "thin blue line"
    }
  ],
  "senses": [
    {
      "categories": [
        "English terms with historical senses"
      ],
      "glosses": [
        "The members the 93rd Regiment of the British Army who met the charge of the Russian cavalry at the Battle of Balaclava in 1854."
      ],
      "raw_glosses": [
        "(historical) The members the 93rd Regiment of the British Army who met the charge of the Russian cavalry at the Battle of Balaclava in 1854."
      ],
      "tags": [
        "historical"
      ]
    },
    {
      "glosses": [
        "Any thinly spread military unit holding firm against attack."
      ],
      "raw_glosses": [
        "(by extension) Any thinly spread military unit holding firm against attack."
      ],
      "tags": [
        "broadly"
      ]
    }
  ],
  "wikipedia": [
    "The Thin Red Line (Battle of Balaclava)"
  ],
  "word": "Thin Red Line"
}