and Tarpaulings. Soldiers and sailors. Soldiers are now popularly called lobsters, because they are turned red when enlisted into the service. But the term was originally applied to a troop of horse soldiers in the Great Rebellion, clad in armour which covered them as a shell.
“Sir William Waller received from London (in 1643) a fresh regiment
of 500 horse, under the command of Sir Arthur Haslerig, which were so
prodigiously armed that they were called by the king's party `the
regiment of lobsters,' because of their bright iron shells with which
they were covered, being perfect cuirassiers, and were the first seen
so armed on either side.” —
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894